content: implement unittests backend for Ozone GBM

ui/ozone/public/ozone_gpu_test_helper.h

Index: ui/ozone/public/ozone_gpu_test_helper.h
diff --git a/ui/ozone/public/ozone_gpu_test_helper.h b/ui/ozone/public/ozone_gpu_test_helper.h
index 5e92b03c97a5d6c6c0d9ef5d917b994d11f4f7b0..1b2682ee955f13609e7d70404e3d7ebd7b017e60 100644
--- a/ui/ozone/public/ozone_gpu_test_helper.h
+++ b/ui/ozone/public/ozone_gpu_test_helper.h
@@ -45,6 +45,21 @@ class OZONE_EXPORT OzoneGpuTestHelper {
   DISALLOW_COPY_AND_ASSIGN(OzoneGpuTestHelper);
 };
 
+// Helper class for tests to initialize both UI and GPU Ozone platform.
+class OZONE_EXPORT OzoneInitializerForTest {
+ public:
+  static std::unique_ptr<OzoneInitializerForTest> Create();
+  ~OzoneInitializerForTest();
+
+ private:
+  OzoneInitializerForTest();
+  bool Initialize();
+
+  std::unique_ptr<OzoneGpuTestHelper> gpu_helper_;
+
+  DISALLOW_COPY_AND_ASSIGN(OzoneInitializerForTest);
+};
+
 }  // namespace ui
 
 #endif  // UI_OZONE_PUBLIC_OZONE_GPU_THREAD_HELPER_H_