Refactor GL bindings so there is no global GLApi or DriverGL.

gpu/command_buffer/service/gl_context_mock.h

Index: gpu/command_buffer/service/gl_context_mock.h
diff --git a/gpu/command_buffer/service/gl_context_mock.h b/gpu/command_buffer/service/gl_context_mock.h
index 5a5a6ade28574f5da0e62fea12d57ffd6d515468..1a63ad32d65c91d09ecc7abed64dc678f637e465 100644
--- a/gpu/command_buffer/service/gl_context_mock.h
+++ b/gpu/command_buffer/service/gl_context_mock.h
@@ -6,11 +6,11 @@
 #define GPU_COMMAND_BUFFER_SERVICE_GL_CONTEXT_MOCK_H_
 
 #include "testing/gmock/include/gmock/gmock.h"
-#include "ui/gl/gl_context_stub_with_extensions.h"
+#include "ui/gl/gl_context_stub.h"
 
 namespace gpu {
 
-class GLContextMock : public gl::GLContextStubWithExtensions {
+class GLContextMock : public gl::GLContextStub {
  public:
   GLContextMock();