gpu: media: RenderingHelper: wait for the display & window to be ready

content/common/gpu/media/rendering_helper.cc

Index: content/common/gpu/media/rendering_helper.cc
diff --git a/content/common/gpu/media/rendering_helper.cc b/content/common/gpu/media/rendering_helper.cc
index 950ae6e71dd07e3eb0a41739e695cab20a9e4825..22ee1c14ff9d4af9473b9c5277de3c3055bddd37 100644
--- a/content/common/gpu/media/rendering_helper.cc
+++ b/content/common/gpu/media/rendering_helper.cc
@@ -13,6 +13,7 @@
 #include "base/command_line.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
 #include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "base/strings/stringize_macros.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/time/time.h"
@@ -39,6 +40,7 @@
 #if defined(USE_OZONE)
 #if defined(OS_CHROMEOS)
 #include "ui/display/chromeos/display_configurator.h"
+#include "ui/display/types/display_constants.h"
 #endif  // defined(OS_CHROMEOS)
 #include "ui/ozone/public/ozone_platform.h"
 #include "ui/ozone/public/ui_thread_gpu.h"
@@ -232,14 +234,26 @@ void RenderingHelper::Initialize(const RenderingHelperParams& params,
   platform_window_delegate_.reset(new RenderingHelper::StubOzoneDelegate());
   window_ = platform_window_delegate_->accelerated_widget();
 #if defined(OS_CHROMEOS)
-  display_configurator_.reset(new ui::DisplayConfigurator());
+  // We hold onto the main loop here to wait for the DisplayController
+  // to give us the size of the display so we can create a window of
+  // the same size.
+  base::MessageLoop::ScopedNestableTaskAllower nest_loop(

[dnicoara, 2015/01/21 19:21:35]

You shouldn't need this anymore.

[llandwerlin-old, 2015/01/22 11:03:18]

Acknowledged.

+      base::MessageLoop::current());
+  display_configurator_.reset(new ui::DisplayConfigurator);
   display_configurator_->Init(true);
   display_configurator_->ForceInitialConfigure(0);
+  // Make sure all the display configuration is applied.
+  base::RunLoop().RunUntilIdle();

[Owen Lin, 2015/01/22 03:46:44]

The correctness of using "RunUntilIdle()" here is highly depending on the
implementation inside display_configurator. If there is another thread involved,
it becomes flaky.
I think we should avoid using it.

[llandwerlin-old, 2015/01/22 11:03:18]

I agree, posting a message to a different thread and waiting for the response
might leave the message loop empty.

+  display_configurator_->SetDisplayMode(ui::MULTIPLE_DISPLAY_STATE_SINGLE);
+  // Make sure all the display configuration is applied.
+  base::RunLoop().RunUntilIdle();
   platform_window_delegate_->platform_window()->SetBounds(
       gfx::Rect(display_configurator_->framebuffer_size()));
 #else
   platform_window_delegate_->platform_window()->SetBounds(gfx::Rect(800, 600));
 #endif
+  // Wait for the window to be resized.
+  base::RunLoop().RunUntilIdle();
 #else
 #error unknown platform
 #endif