[Chromedriver] Add Device Metrics override support to ChromeDriver via Capabilities

chrome/test/chromedriver/chrome/stub_chrome.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/stub_chrome.h"
 #include "chrome/test/chromedriver/chrome/status.h"
 #include "chrome/test/chromedriver/chrome/version.h"
 #include "chrome/test/chromedriver/chrome/web_view.h"
 
 StubChrome::StubChrome() {}
@@ skipping 25 matching lines @@
 }
 
 Status StubChrome::ActivateWebView(const std::string& id) {
   return Status(kOk);
 }
 
 std::string StubChrome::GetOperatingSystemName() {
   return std::string();
 }
 
+bool StubChrome::IsMobileEmulationEnabled() const {
+  return false;
+}
+
 Status StubChrome::Quit() {
   return Status(kOk);
 }