content: implement unittests backend for Ozone GBM

ui/ozone/public/ozone_platform.cc

Index: ui/ozone/public/ozone_platform.cc
diff --git a/ui/ozone/public/ozone_platform.cc b/ui/ozone/public/ozone_platform.cc
index b69bc28927d76d800321b2f58b2c26c66759d21d..e02c324b816be2dad76aa88db0f444594bfb9314 100644
--- a/ui/ozone/public/ozone_platform.cc
+++ b/ui/ozone/public/ozone_platform.cc
@@ -54,6 +54,17 @@ void OzonePlatform::InitializeForGPU() {
 }
 
 // static
+void OzonePlatform::InitializeForTest() {
+  CreateInstance();
+  DCHECK(!g_platform_initialized_ui);
+  DCHECK(!g_platform_initialized_gpu);
+  g_platform_initialized_ui = true;
+  g_platform_initialized_gpu = true;
+  instance_->InitializeTest();
+  DeviceDataManager::CreateInstance();
+}
+
+// static
 OzonePlatform* OzonePlatform::GetInstance() {
   DCHECK(instance_) << "OzonePlatform is not initialized";
   return instance_;