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

ui/gl/gl_implementation.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 "ui/gl/gl_implementation.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "ui/gl/gl_bindings.h"
+#include "ui/gl/gl_gl_api_implementation.h"
 
 namespace gfx {
 
 namespace {
 
 const struct {
   const char* name;
   GLImplementation implementation;
 } kGLImplementationNamePairs[] = {
   { kGLImplementationDesktopName, kGLImplementationDesktopGL },
@@ skipping 140 matching lines @@
   void* proc = GetGLCoreProcAddress(name);
   if (!proc && g_get_proc_address) {
     proc = g_get_proc_address(name);
     if (proc)
       return proc;
   }
 
   return proc;
 }
 
+void InitializeStubGLBindings() {
+  // Only the GL library has stubbed out methods, and this is
+  // platform-independent.
+  InitializeStubGLBindingsGL();
+}
+
 }  // namespace gfx