[ChromeDriver] Support mobile emulation on desktop Chrome.

chrome/test/chromedriver/chrome/chrome_desktop_impl.cc

 // Copyright (c) 2013 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 "chrome/test/chromedriver/chrome/chrome_desktop_impl.h"
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/process/kill.h"
@@ skipping 99 matching lines @@
     if (!id.empty())
       break;
     base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(100));
   }
   if (id.empty())
     return Status(kUnknownError, "page could not be found: " + url);
 
   scoped_ptr<WebView> web_view_tmp(
       new WebViewImpl(id,
                       devtools_http_client_->browser_info(),
-                      devtools_http_client_->CreateClient(id)));
+                      devtools_http_client_->CreateClient(id),
+                      devtools_http_client_->device_metrics()));
   Status status = web_view_tmp->ConnectIfNecessary();
   if (status.IsError())
     return status;
 
   status = web_view_tmp->WaitForPendingNavigations(
       std::string(), deadline - base::TimeTicks::Now(), false);
   if (status.IsOk())
     *web_view = web_view_tmp.Pass();
   return status;
 }
@@ skipping 17 matching lines @@
 }
 
 ChromeDesktopImpl* ChromeDesktopImpl::GetAsDesktop() {
   return this;
 }
 
 std::string ChromeDesktopImpl::GetOperatingSystemName() {
   return base::SysInfo::OperatingSystemName();
 }
 
+bool ChromeDesktopImpl::IsMobileEmulationEnabled() const {
+  return devtools_http_client_->device_metrics() != NULL;
+}
+
 Status ChromeDesktopImpl::QuitImpl() {
   if (!KillProcess(process_))
     return Status(kUnknownError, "cannot kill Chrome");
   return Status(kOk);
 }
 
 const CommandLine& ChromeDesktopImpl::command() const {
   return command_;
 }