Video Player: Enable cast feature by default

The branch point has passes so, this patch enables the feature again.

This patch is the revert of r289621.

BUG=305511
TEST=Confirms the cast icon appears when cast is available.
TBR=hirono@chromium.org

Review URL: https://codereview.chromium.org/496493003

Cr-Commit-Position: refs/heads/master@{#291637}

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

@@ -902,15 +902,6 @@ 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

@@ -10,21 +10,12 @@
 // 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());
+  initialize();
 }.wrap());
 
 /**