Video Player: Disables cast feature by default

The feature will work only when the flag is on.

BUG=305511
TEST=Confirms the cast icon doesn't appear when the flag is off.

Review URL: https://codereview.chromium.org/471903002

Cr-Commit-Position: refs/heads/master@{#289621}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289621 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/extensions/file_manager/private_api_drive.cc

@@ -902,6 +902,15 @@ FileBrowserPrivateGetDownloadUrlFunction::
 }
 
 bool FileBrowserPrivateGetDownloadUrlFunction::RunAsync() {
+  const base::CommandLine* command_line =
+      base::CommandLine::ForCurrentProcess();
+  if (!command_line->HasSwitch(
+          chromeos::switches::kEnableVideoPlayerChromecastSupport)) {
+    SetError("Cast support is disabled.");
+    SetResult(new base::StringValue(""));  // Intentionally returns a blank.
+    return false;
+  }
+
   using extensions::api::file_browser_private::GetShareUrl::Params;
   const scoped_ptr<Params> params(Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params);

ui/file_manager/video_player/js/cast/caster.js

@@ -10,18 +10,34 @@
 // cast extension. This line prevents an exception on using localStorage.
 window.__defineGetter__('localStorage', function() { return {}; });
 
+/**
+ * @type {string}
+ * @const
+ */
+var CAST_COMMAND_LINE_FLAG = 'enable-video-player-chromecast-support';
+
 // THIS IS A TEST APP.
 // TODO(yoshiki): Fix this before launch.
 var APPLICATION_ID = '214CC863';
 
 util.addPageLoadHandler(function() {
+  chrome.commandLinePrivate.hasSwitch(CAST_COMMAND_LINE_FLAG, function(result) {
+    if (result)
+      initialize();
+  }.wrap());
+}.wrap());
+
+/**
+ * Starts initialization of cast-related feature.
+ */
+function initialize() {
   CastExtensionDiscoverer.findInstalledExtension(function(foundId) {
     if (foundId)
       loadCastAPI(initializeApi);
     else
       console.info('No Google Cast extension is installed.');
-  });
-});
+  }.wrap());
+}
 
 /**
  * Executes the given callback after the cast extension is initialized.