[ChromeDriver] Support mobile emulation on desktop Chrome.

chrome/test/chromedriver/chrome/chrome_desktop_impl.cc

Index: chrome/test/chromedriver/chrome/chrome_desktop_impl.cc
diff --git a/chrome/test/chromedriver/chrome/chrome_desktop_impl.cc b/chrome/test/chromedriver/chrome/chrome_desktop_impl.cc
index 8cdd130114b43668f60e315487e0c682c3a70c4a..d7372499fec755d9fc3954f5cbda52c6982e65c1 100644
--- a/chrome/test/chromedriver/chrome/chrome_desktop_impl.cc
+++ b/chrome/test/chromedriver/chrome/chrome_desktop_impl.cc
@@ -117,7 +117,8 @@ Status ChromeDesktopImpl::WaitForPageToLoad(const std::string& 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;
@@ -155,6 +156,10 @@ 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");