ui: Revert gfx::BufferUsage::SCANOUT to gfx::BufferUsage::GPU_READ_WRITE change.

components/mus/gles2/command_buffer_local.cc

Index: components/mus/gles2/command_buffer_local.cc
diff --git a/components/mus/gles2/command_buffer_local.cc b/components/mus/gles2/command_buffer_local.cc
index 4bdad2f46417c986cc76eca309b90f19b4be29a1..2e0535bba42121677e156848bd326c469b9dde1a 100644
--- a/components/mus/gles2/command_buffer_local.cc
+++ b/components/mus/gles2/command_buffer_local.cc
@@ -166,7 +166,7 @@ int32_t CommandBufferLocal::CreateGpuMemoryBufferImage(size_t width,
   scoped_ptr<gfx::GpuMemoryBuffer> buffer(MojoGpuMemoryBufferImpl::Create(
       gfx::Size(static_cast<int>(width), static_cast<int>(height)),
       gpu::ImageFactory::DefaultBufferFormatForImageFormat(internalformat),
-      gfx::BufferUsage::GPU_READ_WRITE));
+      gfx::BufferUsage::SCANOUT));
   if (!buffer)
     return -1;
   return CreateImage(buffer->AsClientBuffer(), width, height, internalformat);