Don't peek messages in the MessagePumpForUI class when we receive our kMsgHaveWork message.

content/gpu/gpu_main.cc

 // Copyright (c) 2012 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 <stdlib.h>
 
 #if defined(OS_WIN)
 #include <dwmapi.h>
 #include <windows.h>
 #endif
@@ skipping 142 matching lines @@
   // safely until the IPC channel is set up, because the detection of
   // early return of a child process is implemented using an IPC
   // channel error. If the IPC channel is not fully set up between the
   // browser and GPU process, and the GPU process crashes or exits
   // early, the browser process will never detect it.  For this reason
   // we defer tearing down the GPU process until receiving the
   // GpuMsg_Initialize message from the browser.
   bool dead_on_arrival = false;
 
 #if defined(OS_WIN)
+  base::MessageLoop::Type loop_type = base::MessageLoop::TYPE_IO;
   // Use a UI message loop because ANGLE and the desktop GL platform can
   // create child windows to render to.
-  base::MessageLoop main_message_loop(base::MessageLoop::TYPE_UI);
+  // TODO(ananta) : Recent changes to the UI message pump class on Windows
+  // will cause delays in tasks getting processed in the GPU process which
+  // will show up on the bots in webgl conformance tests, perf tests etc.
+  // It will be great if we can work around the issues with desktop GL and
+  // avoid creating a child window in the GPU process which requires a UI
+  // message pump.
+  if ((command_line.HasSwitch(switches::kUseGL) &&
+       command_line.GetSwitchValueASCII(switches::kUseGL) == "desktop") ||
+      (command_line.HasSwitch(switches::kUseANGLE) &&
+       command_line.GetSwitchValueASCII(switches::kUseANGLE) == "gl")) {
+    loop_type = base::MessageLoop::TYPE_UI;
+  }
+  base::MessageLoop main_message_loop(loop_type);
 #elif defined(OS_LINUX) && defined(USE_X11)
   // We need a UI loop so that we can grab the Expose events. See GLSurfaceGLX
   // and https://crbug.com/326995.
   base::MessageLoop main_message_loop(base::MessageLoop::TYPE_UI);
   scoped_ptr<ui::PlatformEventSource> event_source =
       ui::PlatformEventSource::CreateDefault();
 #elif defined(OS_LINUX)
   base::MessageLoop main_message_loop(base::MessageLoop::TYPE_DEFAULT);
 #elif defined(OS_MACOSX)
   // This is necessary for CoreAnimation layers hosted in the GPU process to be
@@ skipping 363 matching lines @@
     return true;
   }
 
   return false;
 }
 #endif  // defined(OS_WIN)
 
 }  // namespace.
 
 }  // namespace content