Add hovering feature to AshDevToolsDOMAgent

ash/common/wm_shell.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/common/wm_shell.h"
 
 #include <utility>
 
 #include "ash/common/accelerators/accelerator_controller.h"
 #include "ash/common/accelerators/ash_focus_manager_factory.h"
@@ skipping 75 matching lines @@
 
   // Install the custom factory early on so that views::FocusManagers for Tray,
   // Shelf, and WallPaper could be created by the factory.
   views::FocusManagerFactory::Install(new AshFocusManagerFactory);
 
   wallpaper_controller_.reset(new WallpaperController(blocking_pool_));
 
   // Start devtools server
   devtools_server_ = ui::devtools::UiDevToolsServer::Create(nullptr);
   if (devtools_server_) {
-    auto dom_backend = base::MakeUnique<devtools::AshDevToolsDOMAgent>(this);
+    auto dom_backend = base::MakeUnique<devtools::AshDevToolsDOMAgent>(
+        this, base::MessageLoop::current()->task_runner());

[sadrul, 2016/12/06 20:48:59]

Use base::ThreadTaskRunnerHandle::Get() instead. But maybe we don't need this?
See comment in dom-agent.cc

[Sarmad Hashmi, 2016/12/06 22:54:34]

As discussed, passing main_thread_task_runner to devtools_server instead. Agents
no longer know about any task runners.

     auto css_backend =
         base::MakeUnique<devtools::AshDevToolsCSSAgent>(dom_backend.get());
     auto devtools_client = base::MakeUnique<ui::devtools::UiDevToolsClient>(
         "Ash", devtools_server_.get());
     devtools_client->AddAgent(std::move(dom_backend));
     devtools_client->AddAgent(std::move(css_backend));
     devtools_server_->AttachClient(std::move(devtools_client));
   }
 }
 
@@ skipping 296 matching lines @@
 void WmShell::DeleteToastManager() {
   toast_manager_.reset();
 }
 
 void WmShell::SetAcceleratorController(
     std::unique_ptr<AcceleratorController> accelerator_controller) {
   accelerator_controller_ = std::move(accelerator_controller);
 }
 
 }  // namespace ash