Use stub GL draw/clear calls for browser tests that do not need pixels.

content/public/test/browser_test_base.cc

 // Copyright (c) 2011 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 "content/public/test/browser_test_base.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/stack_trace.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 159 matching lines @@
     allow_test_contexts_ = false;
 #endif
 
 #if defined(USE_AURA)
   if (command_line->HasSwitch(switches::kDisableTestCompositor))
     allow_test_contexts_  = false;
 
   // Use test contexts for browser tests unless they override and force us to
   // use a real context.
   if (allow_test_contexts_ && !use_software_compositing_) {
-    content::ImageTransportFactory::InitializeForUnitTests(
-        scoped_ptr<ui::ContextFactory>(new ui::TestContextFactory));
+    command_line->AppendSwitch(switches::kDisableGLDrawingForTests);
   }
 #endif
 
   // When using real GL contexts, we usually use OSMesa as this works on all
   // bots. The command line can override this behaviour to use a real GPU.
   if (command_line->HasSwitch(switches::kUseGpuInTests))
     allow_osmesa_ = false;
 
   // Some bots pass this flag when they want to use a real GPU.
   if (command_line->HasSwitch("enable-gpu"))
@@ skipping 104 matching lines @@
 #if !defined(USE_AURA) && !defined(OS_MACOSX)
   // TODO(danakj): Remove when GTK linux is no more.
   NOTREACHED();
 #endif
 
   DCHECK(allow_osmesa_) << "Can't use GL with software compositing";
   use_software_compositing_ = true;
 }
 
 }  // namespace content