Reland: Enable NV12 VideoFrames on Mac.

content/renderer/media/renderer_gpu_video_accelerator_factories.cc

Index: content/renderer/media/renderer_gpu_video_accelerator_factories.cc
diff --git a/content/renderer/media/renderer_gpu_video_accelerator_factories.cc b/content/renderer/media/renderer_gpu_video_accelerator_factories.cc
index 399650effc03687ae15d060ab82a9cede5b1a67b..cf9dfe67569f7306e013b6ac5dcdf50e96d068b0 100644
--- a/content/renderer/media/renderer_gpu_video_accelerator_factories.cc
+++ b/content/renderer/media/renderer_gpu_video_accelerator_factories.cc
@@ -225,6 +225,8 @@ RendererGpuVideoAcceleratorFactories::VideoFrameOutputFormat() {
     return media::PIXEL_FORMAT_UNKNOWN;
   cc::ContextProvider::ScopedContextLock lock(context_provider_);
   auto capabilities = context_provider_->ContextCapabilities();
+  if (capabilities.gpu.image_ycbcr_420v)
+    return media::PIXEL_FORMAT_NV12;
   if (capabilities.gpu.image_ycbcr_422)
     return media::PIXEL_FORMAT_UYVY;
   if (capabilities.gpu.texture_rg)