[ChromeDriver] Support mobile emulation on desktop Chrome.

chrome/test/chromedriver/capabilities.cc

Index: chrome/test/chromedriver/capabilities.cc
diff --git a/chrome/test/chromedriver/capabilities.cc b/chrome/test/chromedriver/capabilities.cc
index 518af52734a45f9c3537650db4f25ebdcaa5986d..7357446f4c3c2d7bf2ff7aa8d00fd7c523156d92 100644
--- a/chrome/test/chromedriver/capabilities.cc
+++ b/chrome/test/chromedriver/capabilities.cc
@@ -84,6 +84,25 @@ Status ParseLogPath(const base::Value& option, Capabilities* capabilities) {
   return Status(kOk);
 }
 
+Status ParseDeviceMetrics(const base::Value& option,
+                     Capabilities* capabilities) {
+  const base::DictionaryValue* metrics;
+  if (!option.GetAsDictionary(&metrics))
+    return Status(kUnknownError, "must be a dictionary");
+
+  if (!metrics->GetInteger("width", &(capabilities->device_metrics.width)) ||

[stgao, 2014/04/30 03:32:55]

Code in chromedriver seems not to use "()" to wrap the variable like
"capabilities->device_metrics.width". Maybe remove it if no compile error
occurs?

Same for the two below.

+      !metrics->GetInteger("height", &(capabilities->device_metrics.height)) ||
+      !metrics->GetDouble("pixel_ratio", &(capabilities->device_metrics.device_scale_factor)))

[stgao, 2014/04/30 03:32:55]

over 80 chars.

+    return Status(kUnknownError, "missing or invalid 'metrics'");
+
+  capabilities->device_metrics.emulate_viewport = false;
+  capabilities->device_metrics.fit_window = true;
+  capabilities->device_metrics.text_autosizing = true;
+  capabilities->device_metrics.font_scale_factor = 1;
+
+  return Status(kOk);
+}
+
 Status ParseSwitches(const base::Value& option,
                      Capabilities* capabilities) {
   const base::ListValue* switches_list = NULL;
@@ -272,6 +291,8 @@ Status ParseChromeOptions(
     parser_map["args"] = base::Bind(&ParseSwitches);
     parser_map["binary"] = base::Bind(&ParseFilePath, &capabilities->binary);
     parser_map["detach"] = base::Bind(&ParseBoolean, &capabilities->detach);
+    parser_map["deviceMetrics"] =
+        base::Bind(&ParseDeviceMetrics);
     parser_map["excludeSwitches"] = base::Bind(&ParseExcludeSwitches);
     parser_map["extensions"] = base::Bind(&ParseExtensions);
     parser_map["forceDevToolsScreenshot"] = base::Bind(