Add ash devtools client

ash/common/wm_shell.cc

Index: ash/common/wm_shell.cc
diff --git a/ash/common/wm_shell.cc b/ash/common/wm_shell.cc
index c2e7cf2f8e848d123d5108191b0b8a0c13b3ad1f..da3bb1d99889a48445bfe23ebbe7ec003e9ff701 100644
--- a/ash/common/wm_shell.cc
+++ b/ash/common/wm_shell.cc
@@ -9,6 +9,7 @@
 #include "ash/common/accelerators/accelerator_controller.h"
 #include "ash/common/accelerators/ash_focus_manager_factory.h"
 #include "ash/common/accessibility_delegate.h"
+#include "ash/common/devtools/devtools_dom_agent.h"
 #include "ash/common/focus_cycler.h"
 #include "ash/common/keyboard/keyboard_ui.h"
 #include "ash/common/new_window_client_proxy.h"
@@ -85,6 +86,16 @@ void WmShell::Initialize(const scoped_refptr<base::SequencedWorkerPool>& pool) {
   views::FocusManagerFactory::Install(new AshFocusManagerFactory);
 
   wallpaper_controller_.reset(new WallpaperController(blocking_pool_));
+
+  // Start devtools server
+  devtools_server_ = ui::devtools::UiDevToolsServer::Create();
+  if (devtools_server_) {
+    auto dom_backend = base::MakeUnique<devtools::AshDevToolsDOMAgent>(this);
+    auto devtools_client = base::MakeUnique<ui::devtools::UiDevToolsClient>(
+        "Ash", devtools_server_.get());
+    devtools_client->AddDOMBackend(std::move(dom_backend));
+    devtools_server_->AttachClient(std::move(devtools_client));
+  }
 }
 
 void WmShell::Shutdown() {