[ChromeDriver] Support mobile emulation on desktop Chrome.

chrome/test/chromedriver/chrome/stub_web_view.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 "base/files/file_path.h"
 #include "base/values.h"
 #include "chrome/test/chromedriver/chrome/status.h"
 #include "chrome/test/chromedriver/chrome/stub_web_view.h"
 #include "chrome/test/chromedriver/chrome/ui_events.h"
 
@@ skipping 99 matching lines @@
 }
 
 JavaScriptDialogManager* StubWebView::GetJavaScriptDialogManager() {
   return NULL;
 }
 
 Status StubWebView::OverrideGeolocation(const Geoposition& geoposition) {
   return Status(kOk);
 }
 
+Status StubWebView::OverrideDeviceMetrics(const DeviceMetrics& device_metrics) {
+  return Status(kOk);
+}
+
 Status StubWebView::CaptureScreenshot(std::string* screenshot) {
   return Status(kOk);
 }
 
 Status StubWebView::SetFileInputFiles(
     const std::string& frame,
     const base::DictionaryValue& element,
     const std::vector<base::FilePath>& files) {
   return Status(kOk);
 }
 
 Status StubWebView::TakeHeapSnapshot(scoped_ptr<base::Value>* snapshot) {
   return Status(kOk);
 }