Ensure GL initialization only happens once, and provide common init path

ui/compositor/test/context_factories_for_test.cc

 // Copyright 2013 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/compositor/test/context_factories_for_test.h"
 
 #include "base/command_line.h"
 #include "base/sys_info.h"
 #include "ui/compositor/compositor.h"
 #include "ui/compositor/compositor_switches.h"
 #include "ui/compositor/test/default_context_factory.h"
 #include "ui/compositor/test/test_context_factory.h"
+#include "ui/gl/gl_implementation.h"
 
 namespace ui {
 
 static ContextFactory* g_implicit_factory = NULL;
 
 // static
 void InitializeContextFactoryForTests(bool allow_test_contexts) {
   DCHECK(!g_implicit_factory) <<
       "ContextFactory for tests already initialized.";
 
@@ skipping 10 matching lines @@
   if (base::SysInfo::IsRunningOnChromeOS())
     use_test_contexts = false;
 #endif
 
   if (!allow_test_contexts)
     use_test_contexts = false;
 
   if (use_test_contexts) {
     g_implicit_factory = new ui::TestContextFactory;
   } else {
+    DCHECK_NE(gfx::kGLImplementationNone, gfx::GetGLImplementation());
     DVLOG(1) << "Using DefaultContextFactory";
-    scoped_ptr<ui::DefaultContextFactory> instance(
-        new ui::DefaultContextFactory());
-    if (instance->Initialize())
-      g_implicit_factory = instance.release();
+    g_implicit_factory = new ui::DefaultContextFactory();
   }
   ContextFactory::SetInstance(g_implicit_factory);
 }
 
 void TerminateContextFactoryForTests() {
   ContextFactory::SetInstance(NULL);
   delete g_implicit_factory;
   g_implicit_factory = NULL;
 }
 
 }  // namespace ui