src/cobalt/browser/web_module.cc

/*
 * Copyright 2015 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "cobalt/browser/web_module.h"

#include "base/bind.h"
#include "base/command_line.h"
#include "base/debug/trace_event.h"
#include "base/logging.h"
#include "base/message_loop_proxy.h"
#include "base/optional.h"
#include "base/stringprintf.h"
#include "cobalt/base/address_sanitizer.h"
#include "cobalt/base/tokens.h"
#include "cobalt/browser/switches.h"
#include "cobalt/browser/web_module_stat_tracker.h"
#include "cobalt/debug/debug_server_module.h"
#include "cobalt/dom/csp_delegate_factory.h"
#include "cobalt/dom/storage.h"
#include "cobalt/h5vcc/h5vcc.h"
#include "cobalt/storage/storage_manager.h"

namespace cobalt {
namespace browser {

namespace {

// The maximum number of element depth in the DOM tree. Elements at a level
// deeper than this could be discarded, and will not be rendered.
const int kDOMMaxElementDepth = 32;

#if defined(ENABLE_PARTIAL_LAYOUT_CONTROL)
// Help string for the 'partial_layout' command.
const char kPartialLayoutCommandShortHelp[] =
    "Controls partial layout: on | off | wipe | wipe,off";
const char kPartialLayoutCommandLongHelp[] =
    "Controls partial layout.\n"
    "\n"
    "Syntax:\n"
    "  debug.partial_layout('CMD [, CMD ...]')\n"
    "\n"
    "Where CMD can be:\n"
    "  on   : turn partial layout on.\n"
    "  off  : turn partial layout off.\n"
    "  wipe : wipe the box tree.\n"
    "\n"
    "Example:\n"
    "  debug.partial_layout('off,wipe')\n"
    "\n"
    "To wipe the box tree and turn partial layout off.";
#endif  // defined(ENABLE_PARTIAL_LAYOUT_CONTROL)

}  // namespace

// Private WebModule implementation. Each WebModule owns a single instance of
// this class, which performs all the actual work. All functions of this class
// must be called on the message loop of the WebModule thread, so they
// execute synchronously with respect to one another.
class WebModule::Impl {
 public:
  explicit Impl(const ConstructionData& data);
  ~Impl();

#if defined(ENABLE_DEBUG_CONSOLE)
  debug::DebugServer* debug_server() const {
    return debug_server_module_->debug_server();
  }
#endif  // ENABLE_DEBUG_CONSOLE

  // Called to inject a keyboard event into the web module.
  void InjectKeyboardEvent(const dom::KeyboardEvent::Data& event);

  // Called to execute JavaScript in this WebModule. Sets the |result|
  // output parameter and signals |got_result|.
  void ExecuteJavascript(const std::string& script_utf8,
                         const base::SourceLocation& script_location,
                         base::WaitableEvent* got_result, std::string* result);

  // Clears disables timer related objects
  // so that the message loop can easily exit
  void ClearAllIntervalsAndTimeouts();

#if defined(ENABLE_PARTIAL_LAYOUT_CONTROL)
  void OnPartialLayoutConsoleCommandReceived(const std::string& message);
#endif  // defined(ENABLE_PARTIAL_LAYOUT_CONTROL)

#if defined(ENABLE_WEBDRIVER)
  // Creates a new webdriver::WindowDriver that interacts with the Window that
  // is owned by this WebModule instance.
  void CreateWindowDriver(
      const webdriver::protocol::WindowId& window_id,
      scoped_ptr<webdriver::WindowDriver>* window_driver_out);
#endif

#if defined(ENABLE_DEBUG_CONSOLE)
  void CreateDebugServerIfNull();
#endif  // ENABLE_DEBUG_CONSOLE

 private:
  class DocumentLoadedObserver;

  // Injects a list of custom window attributes into the WebModule's window
  // object.
  void InjectCustomWindowAttributes(
      const Options::InjectedWindowAttributes& attributes);

  // Called by |layout_mananger_| when it produces a render tree. May modify
  // the render tree (e.g. to add a debug overlay), then runs the callback
  // specified in the constructor, |render_tree_produced_callback_|.
  void OnRenderTreeProduced(const LayoutResults& layout_results);

  void OnCspPolicyChanged();

  scoped_refptr<script::GlobalEnvironment> global_environment() {
    DCHECK(thread_checker_.CalledOnValidThread());
    return global_environment_;
  }

  void OnError(const std::string& error) {
    error_callback_.Run(window_->location()->url(), error);
  }

  // Thread checker ensures all calls to the WebModule are made from the same
  // thread that it is created in.
  base::ThreadChecker thread_checker_;

  std::string name_;

  // Simple flag used for basic error checking.
  bool is_running_;

  // CSS parser.
  scoped_ptr<css_parser::Parser> css_parser_;

  // DOM (HTML / XML) parser.
  scoped_ptr<dom_parser::Parser> dom_parser_;

  // FetcherFactory that is used to create a fetcher according to URL.
  scoped_ptr<loader::FetcherFactory> fetcher_factory_;

  // ImageCache that is used to manage image cache logic.
  scoped_ptr<loader::image::ImageCache> image_cache_;

  // RemoteTypefaceCache that is used to manage loading and caching typefaces
  // from URLs.
  scoped_ptr<loader::font::RemoteTypefaceCache> remote_typeface_cache_;

  // Interface between LocalStorage and the Storage Manager.
  scoped_ptr<dom::LocalStorageDatabase> local_storage_database_;

  // Stats for the web module. Both the dom stat tracker and layout stat
  // tracker are contained within it.
  scoped_ptr<browser::WebModuleStatTracker> web_module_stat_tracker_;

  // JavaScript engine for the browser.
  scoped_ptr<script::JavaScriptEngine> javascript_engine_;

  // JavaScript Global Object for the browser. There should be one per window,
  // but since there is only one window, we can have one per browser.
  scoped_refptr<script::GlobalEnvironment> global_environment_;

  // Used by |Console| to obtain a JavaScript stack trace.
  scoped_ptr<script::ExecutionState> execution_state_;

  // Interface for the document to execute JavaScript code.
  scoped_ptr<script::ScriptRunner> script_runner_;

  // Object to register and retrieve MediaSource object with a string key.
  scoped_ptr<dom::MediaSource::Registry> media_source_registry_;

  // The Window object wraps all DOM-related components.
  scoped_refptr<dom::Window> window_;

  // Cache a WeakPtr in the WebModule that is bound to the Window's message loop
  // so we can ensure that all subsequently created WeakPtr's are also bound to
  // the same loop.
  // See the documentation in base/memory/weak_ptr.h for details.
  base::WeakPtr<dom::Window> window_weak_;

  // Environment Settings object
  scoped_ptr<dom::DOMSettings> environment_settings_;

  // Called by |OnRenderTreeProduced|.
  OnRenderTreeProducedCallback render_tree_produced_callback_;

  // Called by |OnError|.
  OnErrorCallback error_callback_;

  // Triggers layout whenever the document changes.
  scoped_ptr<layout::LayoutManager> layout_manager_;

#if defined(ENABLE_DEBUG_CONSOLE)
  // Allows the debugger to add render components to the web module.
  // Used for DOM node highlighting and overlay messages.
  scoped_ptr<debug::RenderOverlay> debug_overlay_;
  render_tree::ResourceProvider* resource_provider_;

  // The core of the debugging system, described here:
  // https://docs.google.com/document/d/1lZhrBTusQZJsacpt21J3kPgnkj7pyQObhFqYktvm40Y
  // Created lazily when accessed via |GetDebugServer|.
  scoped_ptr<debug::DebugServerModule> debug_server_module_;
#endif  // ENABLE_DEBUG_CONSOLE

  // DocumentObserver that observes the loading document.
  scoped_ptr<DocumentLoadedObserver> document_load_observer_;

#if defined(ENABLE_PARTIAL_LAYOUT_CONTROL)
  // Handles the 'partial_layout' command.
  scoped_ptr<base::ConsoleCommandManager::CommandHandler>
      partial_layout_command_handler_;
#endif  // defined(ENABLE_PARTIAL_LAYOUT_CONTROL)
};

class WebModule::Impl::DocumentLoadedObserver : public dom::DocumentObserver {
 public:
  typedef std::vector<base::Closure> ClosureVector;
  explicit DocumentLoadedObserver(const ClosureVector& loaded_callbacks)
      : loaded_callbacks_(loaded_callbacks) {}
  // Called at most once, when document and all referred resources are loaded.
  void OnLoad() OVERRIDE {
    for (size_t i = 0; i < loaded_callbacks_.size(); ++i) {
      loaded_callbacks_[i].Run();
    }
  }

  void OnMutation() OVERRIDE{};

 private:
  ClosureVector loaded_callbacks_;
};

WebModule::Impl::Impl(const ConstructionData& data)
    : name_(data.options.name), is_running_(false) {
  css_parser_ = css_parser::Parser::Create();
  DCHECK(css_parser_);

  dom_parser_.reset(new dom_parser::Parser(
      kDOMMaxElementDepth,
      base::Bind(&WebModule::Impl::OnError, base::Unretained(this))));
  DCHECK(dom_parser_);

  fetcher_factory_.reset(new loader::FetcherFactory(
      data.network_module, data.options.extra_web_file_dir));
  DCHECK(fetcher_factory_);

  DCHECK_LE(0, data.options.image_cache_capacity);
  image_cache_ = loader::image::CreateImageCache(
      base::StringPrintf("Memory.%s.ImageCache", name_.c_str()),
      static_cast<uint32>(data.options.image_cache_capacity),
      data.resource_provider, fetcher_factory_.get());
  DCHECK(image_cache_);

  DCHECK_LE(0, data.options.remote_typeface_cache_capacity);
  remote_typeface_cache_ = loader::font::CreateRemoteTypefaceCache(
      base::StringPrintf("Memory.%s.RemoteTypefaceCache", name_.c_str()),
      static_cast<uint32>(data.options.remote_typeface_cache_capacity),
      data.resource_provider, fetcher_factory_.get());
  DCHECK(remote_typeface_cache_);

  local_storage_database_.reset(
      new dom::LocalStorageDatabase(data.network_module->storage_manager()));
  DCHECK(local_storage_database_);

  web_module_stat_tracker_.reset(
      new browser::WebModuleStatTracker(name_, data.options.track_event_stats));
  DCHECK(web_module_stat_tracker_);

  javascript_engine_ = script::JavaScriptEngine::CreateEngine();
  DCHECK(javascript_engine_);

  global_environment_ = javascript_engine_->CreateGlobalEnvironment();
  DCHECK(global_environment_);

  execution_state_ =
      script::ExecutionState::CreateExecutionState(global_environment_);
  DCHECK(execution_state_);

  script_runner_ =
      script::ScriptRunner::CreateScriptRunner(global_environment_);
  DCHECK(script_runner_);

  media_source_registry_.reset(new dom::MediaSource::Registry);

  window_ = new dom::Window(
      data.window_dimensions.width(), data.window_dimensions.height(),
      css_parser_.get(), dom_parser_.get(), fetcher_factory_.get(),
      data.resource_provider, image_cache_.get(), remote_typeface_cache_.get(),
      local_storage_database_.get(), data.media_module, data.media_module,
      execution_state_.get(), script_runner_.get(),
      media_source_registry_.get(),
      web_module_stat_tracker_->dom_stat_tracker(), data.initial_url,
      data.network_module->GetUserAgent(),
      data.network_module->preferred_language(),
      data.options.navigation_callback,
      base::Bind(&WebModule::Impl::OnError, base::Unretained(this)),
      data.network_module->cookie_jar(), data.network_module->GetPostSender(),
      data.options.location_policy, data.options.csp_enforcement_mode,
      base::Bind(&WebModule::Impl::OnCspPolicyChanged, base::Unretained(this)),
      data.options.csp_insecure_allowed_token);
  DCHECK(window_);

  window_weak_ = base::AsWeakPtr(window_.get());
  DCHECK(window_weak_);

  environment_settings_.reset(new dom::DOMSettings(
      kDOMMaxElementDepth, fetcher_factory_.get(), data.network_module, window_,
      media_source_registry_.get(), javascript_engine_.get(),
      global_environment_.get(), data.options.dom_settings_options));
  DCHECK(environment_settings_);

  global_environment_->CreateGlobalObject(window_, environment_settings_.get());

  render_tree_produced_callback_ = data.render_tree_produced_callback;
  DCHECK(!render_tree_produced_callback_.is_null());

  error_callback_ = data.error_callback;
  DCHECK(!error_callback_.is_null());

  layout_manager_.reset(new layout::LayoutManager(
      window_.get(), base::Bind(&WebModule::Impl::OnRenderTreeProduced,
                                base::Unretained(this)),
      data.options.layout_trigger, data.dom_max_element_depth,
      data.layout_refresh_rate, data.network_module->preferred_language(),
      web_module_stat_tracker_->layout_stat_tracker()));
  DCHECK(layout_manager_);

#if defined(ENABLE_DEBUG_CONSOLE)
  debug_overlay_.reset(
      new debug::RenderOverlay(data.render_tree_produced_callback));
  resource_provider_ = data.resource_provider;
#endif  // ENABLE_DEBUG_CONSOLE

#if !defined(COBALT_FORCE_CSP)
  if (data.options.csp_enforcement_mode == dom::kCspEnforcementDisable) {
    // If CSP is disabled, enable eval(). Otherwise, it will be enabled by
    // a CSP directive.
    global_environment_->EnableEval();
  }
#endif

  global_environment_->SetReportEvalCallback(
      base::Bind(&dom::CspDelegate::ReportEval,
                 base::Unretained(window_->document()->csp_delegate())));

  InjectCustomWindowAttributes(data.options.injected_window_attributes);

  if (!data.options.loaded_callbacks.empty()) {
    document_load_observer_.reset(
        new DocumentLoadedObserver(data.options.loaded_callbacks));
    window_->document()->AddObserver(document_load_observer_.get());
  }

  is_running_ = true;
}

WebModule::Impl::~Impl() {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(is_running_);
  is_running_ = false;
  global_environment_->SetReportEvalCallback(base::Closure());
  window_->DispatchEvent(new dom::Event(base::Tokens::unload()));
  document_load_observer_.reset();

#if defined(ENABLE_DEBUG_CONSOLE)
  debug_overlay_.reset();
  debug_server_module_.reset();
#endif  // ENABLE_DEBUG_CONSOLE

  layout_manager_.reset();
  environment_settings_.reset();
  window_weak_.reset();
  window_ = NULL;
  media_source_registry_.reset();
  script_runner_.reset();
  execution_state_.reset();
  global_environment_ = NULL;
  javascript_engine_.reset();
  web_module_stat_tracker_.reset();
  local_storage_database_.reset();
  remote_typeface_cache_.reset();
  image_cache_.reset();
  fetcher_factory_.reset();
  dom_parser_.reset();
  css_parser_.reset();
}

void WebModule::Impl::InjectKeyboardEvent(
    const dom::KeyboardEvent::Data& event) {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(is_running_);
  DCHECK(window_);

  // Construct the DOM object from the keyboard event builder and inject it
  // into the window.
  scoped_refptr<dom::KeyboardEvent> keyboard_event(
      new dom::KeyboardEvent(event));

  // Give the stat tracker a chance to start tracking the event before it is
  // injected.
  web_module_stat_tracker_->OnInjectEvent(keyboard_event);

  window_->InjectEvent(keyboard_event);
}

void WebModule::Impl::ExecuteJavascript(
    const std::string& script_utf8, const base::SourceLocation& script_location,
    base::WaitableEvent* got_result, std::string* result) {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(is_running_);
  DCHECK(script_runner_);
  *result = script_runner_->Execute(script_utf8, script_location);
  got_result->Signal();
}

void WebModule::Impl::ClearAllIntervalsAndTimeouts() {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(window_);
  window_->DestroyTimers();
}

void WebModule::Impl::OnRenderTreeProduced(
    const LayoutResults& layout_results) {
  // Notify the stat tracker that a render tree has been produced. This signals
  // the end of previous event tracking, and triggers flushing of periodic
  // counts.
  web_module_stat_tracker_->OnRenderTreeProduced();

  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(is_running_);
#if defined(ENABLE_DEBUG_CONSOLE)
  debug_overlay_->OnRenderTreeProduced(layout_results);
#else  // ENABLE_DEBUG_CONSOLE
  render_tree_produced_callback_.Run(layout_results);
#endif  // ENABLE_DEBUG_CONSOLE
}

#if defined(ENABLE_PARTIAL_LAYOUT_CONTROL)
void WebModule::Impl::OnPartialLayoutConsoleCommandReceived(
    const std::string& message) {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(is_running_);
  DCHECK(window_);
  DCHECK(window_->document());
  window_->document()->SetPartialLayout(message);
}
#endif  // defined(ENABLE_PARTIAL_LAYOUT_CONTROL)

void WebModule::Impl::OnCspPolicyChanged() {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(is_running_);
  DCHECK(window_);
  DCHECK(window_->document());
  DCHECK(window_->document()->csp_delegate());

  std::string eval_disabled_message;
  bool allow_eval =
      window_->document()->csp_delegate()->AllowEval(&eval_disabled_message);
  if (allow_eval) {
    global_environment_->EnableEval();
  } else {
    global_environment_->DisableEval(eval_disabled_message);
  }
}

#if defined(ENABLE_WEBDRIVER)
void WebModule::Impl::CreateWindowDriver(
    const webdriver::protocol::WindowId& window_id,
    scoped_ptr<webdriver::WindowDriver>* window_driver_out) {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(is_running_);
  DCHECK(window_);
  DCHECK(window_weak_);
  DCHECK(window_->document());
  DCHECK(global_environment_);

  window_driver_out->reset(new webdriver::WindowDriver(
      window_id, window_weak_,
      base::Bind(&WebModule::Impl::global_environment, base::Unretained(this)),
      base::MessageLoopProxy::current()));
}
#endif  // defined(ENABLE_WEBDRIVER)

#if defined(ENABLE_DEBUG_CONSOLE)
void WebModule::Impl::CreateDebugServerIfNull() {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(is_running_);
  DCHECK(window_);
  DCHECK(global_environment_);
  DCHECK(resource_provider_);

  if (debug_server_module_) {
    return;
  }

  debug_server_module_.reset(new debug::DebugServerModule(
      window_->console(), global_environment_, debug_overlay_.get(),
      resource_provider_, window_));
}
#endif  // defined(ENABLE_DEBUG_CONSOLE)

void WebModule::Impl::InjectCustomWindowAttributes(
    const Options::InjectedWindowAttributes& attributes) {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(global_environment_);

  for (Options::InjectedWindowAttributes::const_iterator iter =
           attributes.begin();
       iter != attributes.end(); ++iter) {
    global_environment_->Bind(iter->first, iter->second.Run());
  }
}

WebModule::DestructionObserver::DestructionObserver(WebModule* web_module)
    : web_module_(web_module) {}

void WebModule::DestructionObserver::WillDestroyCurrentMessageLoop() {
  web_module_->impl_.reset();
}

WebModule::Options::Options()
    : name("WebModule"),
      layout_trigger(layout::LayoutManager::kOnDocumentMutation),
      image_cache_capacity(COBALT_IMAGE_CACHE_SIZE_IN_BYTES),
      remote_typeface_cache_capacity(
          COBALT_REMOTE_TYPEFACE_CACHE_SIZE_IN_BYTES),
      csp_enforcement_mode(dom::kCspEnforcementEnable),
      csp_insecure_allowed_token(0),
      track_event_stats(false) {}

WebModule::WebModule(
    const GURL& initial_url,
    const OnRenderTreeProducedCallback& render_tree_produced_callback,
    const OnErrorCallback& error_callback, media::MediaModule* media_module,
    network::NetworkModule* network_module, const math::Size& window_dimensions,
    render_tree::ResourceProvider* resource_provider, float layout_refresh_rate,
    const Options& options)
    : thread_(options.name.c_str()) {
  ConstructionData construction_data(
      initial_url, render_tree_produced_callback, error_callback, media_module,
      network_module, window_dimensions, resource_provider, kDOMMaxElementDepth,
      layout_refresh_rate, options);

#if defined(COBALT_BUILD_TYPE_DEBUG)
  // Non-optimized builds require a bigger stack size.
  const size_t kBaseStackSize = 2 * 1024 * 1024;
#else
  const size_t kBaseStackSize = 256 * 1024;
#endif

  // Start the dedicated thread and create the internal implementation
  // object on that thread.
  size_t stack_size = kBaseStackSize + base::kAsanAdditionalStackSize;
  thread_.StartWithOptions(
      base::Thread::Options(MessageLoop::TYPE_DEFAULT, stack_size));
  DCHECK(message_loop());

  message_loop()->PostTask(
      FROM_HERE, base::Bind(&WebModule::Initialize, base::Unretained(this),
                            construction_data));

  // Block this thread until the initialization is complete.
  // TODO: Figure out why this is necessary.
  // It would be preferable to return immediately and let the WebModule
  // continue in its own time, but without this wait there is a race condition
  // such that inline scripts may be executed before the document elements they
  // operate on are present.
  base::WaitableEvent is_initialized(true, false);
  message_loop()->PostTask(FROM_HERE,
                           base::Bind(&base::WaitableEvent::Signal,
                                      base::Unretained(&is_initialized)));
  is_initialized.Wait();

#if defined(ENABLE_PARTIAL_LAYOUT_CONTROL)
  CommandLine* command_line = CommandLine::ForCurrentProcess();
  if (command_line->HasSwitch(browser::switches::kPartialLayout)) {
    const std::string partial_layout_string =
        command_line->GetSwitchValueASCII(browser::switches::kPartialLayout);
    OnPartialLayoutConsoleCommandReceived(partial_layout_string);
  }
  partial_layout_command_handler_.reset(
      new base::ConsoleCommandManager::CommandHandler(
          browser::switches::kPartialLayout,
          base::Bind(&WebModule::OnPartialLayoutConsoleCommandReceived,
                     base::Unretained(this)),
          kPartialLayoutCommandShortHelp, kPartialLayoutCommandLongHelp));
#endif  // defined(ENABLE_PARTIAL_LAYOUT_CONTROL)
}

WebModule::~WebModule() {
  DCHECK(message_loop());

#if defined(ENABLE_PARTIAL_LAYOUT_CONTROL)
  partial_layout_command_handler_.reset();
#endif  // defined(ENABLE_PARTIAL_LAYOUT_CONTROL)

  // Create a destruction observer to shut down the WebModule once all pending
  // tasks have been executed and the message loop is about to be destroyed.
  // This allows us to safely stop the thread, drain the task queue, then
  // destroy the internal components before the message loop is set to NULL.
  // No posted tasks will be executed once the thread is stopped.
  DestructionObserver destruction_observer(this);
  message_loop()->PostTask(FROM_HERE,
                           base::Bind(&MessageLoop::AddDestructionObserver,
                                      base::Unretained(message_loop()),
                                      base::Unretained(&destruction_observer)));

  base::WaitableEvent did_register_shutdown_observer(true, false);
  message_loop()->PostTask(
      FROM_HERE, base::Bind(&base::WaitableEvent::Signal,
                            base::Unretained(&did_register_shutdown_observer)));
  did_register_shutdown_observer.Wait();

  // This will cancel the timers for tasks, which help the thread exit
  ClearAllIntervalsAndTimeouts();

  // Stop the thread. This will cause the destruction observer to be notified.
  thread_.Stop();
}

void WebModule::Initialize(const ConstructionData& data) {
  DCHECK_EQ(MessageLoop::current(), message_loop());
  impl_.reset(new Impl(data));
}

void WebModule::InjectKeyboardEvent(const dom::KeyboardEvent::Data& event) {
  TRACE_EVENT1("cobalt::browser", "WebModule::InjectKeyboardEvent()", "type",
               event.type);
  DCHECK(message_loop());
  DCHECK(impl_);

  message_loop()->PostTask(FROM_HERE,
                           base::Bind(&WebModule::Impl::InjectKeyboardEvent,
                                      base::Unretained(impl_.get()), event));
}

std::string WebModule::ExecuteJavascript(
    const std::string& script_utf8,
    const base::SourceLocation& script_location) {
  TRACE_EVENT0("cobalt::browser", "WebModule::ExecuteJavascript()");
  DCHECK(message_loop());
  DCHECK(impl_);

  base::WaitableEvent got_result(true, false);
  std::string result;
  message_loop()->PostTask(
      FROM_HERE, base::Bind(&WebModule::Impl::ExecuteJavascript,
                            base::Unretained(impl_.get()), script_utf8,
                            script_location, &got_result, &result));
  got_result.Wait();
  return result;
}

void WebModule::ClearAllIntervalsAndTimeouts() {
  TRACE_EVENT0("cobalt::browser", "WebModule::ClearAllIntervalsAndTimeouts()");
  DCHECK(message_loop());
  DCHECK(impl_);

  if (impl_) {
    message_loop()->PostTask(
        FROM_HERE, base::Bind(&WebModule::Impl::ClearAllIntervalsAndTimeouts,
                              base::Unretained(impl_.get())));
  }
}

#if defined(ENABLE_PARTIAL_LAYOUT_CONTROL)
void WebModule::OnPartialLayoutConsoleCommandReceived(
    const std::string& message) {
  DCHECK(message_loop());
  DCHECK(impl_);

  message_loop()->PostTask(
      FROM_HERE,
      base::Bind(&WebModule::Impl::OnPartialLayoutConsoleCommandReceived,
                 base::Unretained(impl_.get()), message));
}
#endif  // defined(ENABLE_PARTIAL_LAYOUT_CONTROL)

#if defined(ENABLE_WEBDRIVER)
scoped_ptr<webdriver::WindowDriver> WebModule::CreateWindowDriver(
    const webdriver::protocol::WindowId& window_id) {
  DCHECK(message_loop());
  DCHECK(impl_);

  scoped_ptr<webdriver::WindowDriver> window_driver;
  message_loop()->PostTask(FROM_HERE,
                           base::Bind(&WebModule::Impl::CreateWindowDriver,
                                      base::Unretained(impl_.get()), window_id,
                                      base::Unretained(&window_driver)));

  base::WaitableEvent window_driver_created(true, false);
  message_loop()->PostTask(
      FROM_HERE, base::Bind(&base::WaitableEvent::Signal,
                            base::Unretained(&window_driver_created)));
  window_driver_created.Wait();

  return window_driver.Pass();
}
#endif  // defined(ENABLE_WEBDRIVER)

#if defined(ENABLE_DEBUG_CONSOLE)
// May be called from any thread.
debug::DebugServer* WebModule::GetDebugServer() {
  DCHECK(message_loop());
  DCHECK(impl_);

  message_loop()->PostTask(FROM_HERE,
                           base::Bind(&WebModule::Impl::CreateDebugServerIfNull,
                                      base::Unretained(impl_.get())));

  base::WaitableEvent debug_server_created(true, false);
  message_loop()->PostTask(FROM_HERE,
                           base::Bind(&base::WaitableEvent::Signal,
                                      base::Unretained(&debug_server_created)));

  debug_server_created.Wait();
  return impl_->debug_server();
}
#endif  // defined(ENABLE_DEBUG_CONSOLE)

}  // namespace browser
}  // namespace cobalt