command_buffer_gles2: Implement EGL default Display as a global object

gpu/command_buffer/service/gles2_cmd_decoder_mock.h

Index: gpu/command_buffer/service/gles2_cmd_decoder_mock.h
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_mock.h b/gpu/command_buffer/service/gles2_cmd_decoder_mock.h
index 396f531a3a2ea6fe7a77899704f8694fb3d7de98..636dc14eaf31c8b351abd50db5e36185d5a975a6 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_mock.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_mock.h
@@ -52,6 +52,7 @@ class MockGLES2Decoder : public GLES2Decoder {
                     const std::vector<int32_t>& attribs));
   MOCK_METHOD1(Destroy, void(bool have_context));
   MOCK_METHOD1(SetSurface, void(const scoped_refptr<gfx::GLSurface>& surface));
+  MOCK_METHOD0(ReleaseSurface, void());
   MOCK_METHOD1(ProduceFrontBuffer, void(const Mailbox& mailbox));
   MOCK_METHOD1(ResizeOffscreenFrameBuffer, bool(const gfx::Size& size));
   MOCK_METHOD0(MakeCurrent, bool());