cc: Make cc_unittests opt into real GL NullDraw contexts.

cc/test/layer_tree_pixel_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 "cc/test/layer_tree_pixel_test.h"
 
 #include "base/command_line.h"
 #include "base/path_service.h"
 #include "cc/base/switches.h"
 #include "cc/layers/solid_color_layer.h"
 #include "cc/layers/texture_layer.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/output/copy_output_result.h"
 #include "cc/resources/texture_mailbox.h"
 #include "cc/test/paths.h"
 #include "cc/test/pixel_comparator.h"
 #include "cc/test/pixel_test_output_surface.h"
 #include "cc/test/pixel_test_software_output_device.h"
 #include "cc/test/pixel_test_utils.h"
 #include "cc/test/test_in_process_context_provider.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "gpu/command_buffer/client/gl_in_process_context.h"
 #include "gpu/command_buffer/client/gles2_implementation.h"
 
 using gpu::gles2::GLES2Interface;
 
 namespace cc {
 
 LayerTreePixelTest::LayerTreePixelTest()
-    : pixel_comparator_(new ExactPixelComparator(true)),
+    : enable_pixel_output_(new gfx::DisableNullDrawGLBindings),
+      pixel_comparator_(new ExactPixelComparator(true)),
       test_type_(GL_WITH_DEFAULT),
       pending_texture_mailbox_callbacks_(0),
       impl_side_painting_(true) {}
 
 LayerTreePixelTest::~LayerTreePixelTest() {}
 
 scoped_ptr<OutputSurface> LayerTreePixelTest::CreateOutputSurface(
     bool fallback) {
   gfx::Size surface_expansion_size(40, 60);
   scoped_ptr<PixelTestOutputSurface> output_surface;
@@ skipping 325 matching lines @@
 
   *texture_mailbox = TextureMailbox(mailbox, GL_TEXTURE_2D, sync_point);
   *release_callback = SingleReleaseCallback::Create(
       base::Bind(&LayerTreePixelTest::ReleaseTextureMailbox,
                  base::Unretained(this),
                  base::Passed(&context),
                  texture_id));
 }
 
 }  // namespace cc