Back out r58711. It appears to have caused video/media-related ui_tests...

chrome/renderer/render_thread.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/render_thread.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <vector>
@@ skipping 927 matching lines @@
   WebRuntimeFeatures::enableSessionStorage(
       !command_line.HasSwitch(switches::kDisableSessionStorage));
 
   WebRuntimeFeatures::enableIndexedDatabase(
       command_line.HasSwitch(switches::kEnableIndexedDatabase));
 
   WebRuntimeFeatures::enableGeolocation(
       !command_line.HasSwitch(switches::kDisableGeolocation));
 
   WebRuntimeFeatures::enableWebGL(
-      !command_line.HasSwitch(switches::kDisableExperimentalWebGL));
+      command_line.HasSwitch(switches::kEnableExperimentalWebGL));
 
   WebRuntimeFeatures::enablePushState(true);
 
   WebRuntimeFeatures::enableTouch(
       command_line.HasSwitch(switches::kEnableTouch));
 
   WebRuntimeFeatures::enableDeviceMotion(
       command_line.HasSwitch(switches::kEnableDeviceMotion));
 
   WebRuntimeFeatures::enableDeviceOrientation(
@@ skipping 140 matching lines @@
 
 scoped_refptr<base::MessageLoopProxy>
 RenderThread::GetFileThreadMessageLoopProxy() {
   DCHECK(message_loop() == MessageLoop::current());
   if (!file_thread_.get()) {
     file_thread_.reset(new base::Thread("Renderer::FILE"));
     file_thread_->Start();
   }
   return file_thread_->message_loop_proxy();
 }