content: implement unittests backend for Ozone GBM

ui/ozone/public/ozone_gpu_test_helper.cc

Index: ui/ozone/public/ozone_gpu_test_helper.cc
diff --git a/ui/ozone/public/ozone_gpu_test_helper.cc b/ui/ozone/public/ozone_gpu_test_helper.cc
index fe5a17b31cdb9775f7337863131e9ac4c3f14c02..ab7fea96026f44e5301431347aea2610c27a325b 100644
--- a/ui/ozone/public/ozone_gpu_test_helper.cc
+++ b/ui/ozone/public/ozone_gpu_test_helper.cc
@@ -4,6 +4,7 @@
 
 #include "ui/ozone/public/ozone_gpu_test_helper.h"
 
+#include "base/run_loop.h"
 #include "base/thread_task_runner_handle.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_message.h"
@@ -131,4 +132,35 @@ bool OzoneGpuTestHelper::Initialize(
   return true;
 }
 
+// static
+scoped_ptr<OzoneInitializerForTest> OzoneInitializerForTest::Create() {
+  scoped_ptr<OzoneInitializerForTest> self(new OzoneInitializerForTest());
+  if (!self->Initialize())
+    return nullptr;
+  return self.Pass();
+}
+
+OzoneInitializerForTest::OzoneInitializerForTest() {}
+
+OzoneInitializerForTest::~OzoneInitializerForTest() {}
+
+bool OzoneInitializerForTest::Initialize() {
+  // On Ozone, the backend initializes the event system using a UI thread.
+  message_loop_.reset(new base::MessageLoopForUI);

[spang, 2015/12/02 17:00:03]

This is a library component. I'm very unconvinced about creating a message loop
for the main thread here. The main thread message loop is the main program's
problem, so it belongs in either the test or test harness.

[dshwang, 2015/12/08 01:12:38]

There are pros and cons.

If the loop should belong to test harness, gl_image_test_support and
content_test_suite needs additional ozone specific code.

// time to initialize
#if defined(USE_OZONE)
message_loop_.reset(new base::MessageLoopForUI);
#endif

// time to destory
#if defined(USE_OZONE)
message_loop_.reset();
#endif

Worth to note is that all code also creates OzoneInitializerForTest at the time.
So it's not bad that OzoneInitializerForTest creates the loop by itself.

[dshwang, 2015/12/08 22:19:33]

At least, gl_image_test_support and content_test_suite don't need message_loop
so they don't create it.

Do you want to create message loop for all platforms, although only ozone really
requires it?

+
+  OzonePlatform::InitializeForUI();
+  OzonePlatform::InitializeForGPU();
+  gpu_helper_.reset(new OzoneGpuTestHelper);
+  if (!gpu_helper_->Initialize(base::ThreadTaskRunnerHandle::Get(),
+                               base::ThreadTaskRunnerHandle::Get())) {
+    return false;
+  }
+  {
+    base::MessageLoop::ScopedNestableTaskAllower allow(
+        base::MessageLoop::current());
+    base::RunLoop().RunUntilIdle();
+  }
+  return true;
+}
+
 }  // namespace ui