[ChromeDriver] Support mobile emulation on desktop Chrome.

chrome/test/chromedriver/session_commands.cc

Index: chrome/test/chromedriver/session_commands.cc
diff --git a/chrome/test/chromedriver/session_commands.cc b/chrome/test/chromedriver/session_commands.cc
index b0ad052b4d51cf0fdb40128d450b86ff33c2fde0..b16f5e166cd225a69fec42a4959d8b3860710670 100644
--- a/chrome/test/chromedriver/session_commands.cc
+++ b/chrome/test/chromedriver/session_commands.cc
@@ -99,6 +99,17 @@ scoped_ptr<base::DictionaryValue> CreateCapabilities(Chrome* chrome) {
   return caps.Pass();
 }
 
+Status InitDeviceMetricsOverride(
+    Session* session,
+    DeviceMetrics* device_metrics)
+{
+  WebView* web_view;
+  session->chrome->GetWebViewById(session->window, &web_view);
+  Status status = web_view->OverrideDeviceMetrics(*device_metrics);
+  if (status.IsOk())
+    session->overridden_device_metrics.reset(new DeviceMetrics(*device_metrics));
+  return status;
+}
 
 Status InitSessionHelper(
     const InitSessionParams& bound_params,
@@ -149,6 +160,11 @@ Status InitSessionHelper(
   }
 
   session->window = web_view_ids.front();
+
+  if (capabilities.device_metrics.width != 0) {

[stgao, 2014/05/03 00:15:20]

Instead of creating an instance of struct |device_metrics| in capabilities.h, we
could wrap it up with a scoped_ptr.

In this way, we could test the scoped_ptr to check if an emulation is requested.

[sam.rawlins, 2014/05/06 23:51:46]

Done.

+    InitDeviceMetricsOverride(session, &capabilities.device_metrics);
+  }
+
   session->detach = capabilities.detach;
   session->force_devtools_screenshot = capabilities.force_devtools_screenshot;
   session->capabilities = CreateCapabilities(session->chrome.get());