webgl, cros: make chromium image work on ChromeOS.

BGRX_8888 Gpu Memory Buffer is not always supported. Before using it, check it
available first.

BUG=746069
TEST=run WebGL Aquarium on eve

Change-Id: Ib49784a7706cfebd8edd572011c874b18f805f86
Reviewed-on: https://chromium-review.googlesource.com/576616Reviewed-by: Dongseong Hwang <dongseong.hwang@intel.com>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Dongseong Hwang <dongseong.hwang@intel.com>
Cr-Commit-Position: refs/heads/master@{#488374}

third_party/WebKit/Source/platform/graphics/gpu/DEPS

 include_rules = [
     # For tests only!
     "+gpu/command_buffer/client/gles2_interface_stub.h",
-    "+gpu/command_buffer/common/capabilities.h"
+    "+gpu/command_buffer/common/capabilities.h",
+    "+gpu/command_buffer/common/gpu_memory_buffer_support.h"
 ]

third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.cpp

@@ -39,6 +39,7 @@
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/command_buffer/client/gpu_memory_buffer_manager.h"
 #include "gpu/command_buffer/common/capabilities.h"
+#include "gpu/command_buffer/common/gpu_memory_buffer_support.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/AcceleratedStaticBitmapImage.h"
 #include "platform/graphics/GraphicsLayer.h"
@@ -1178,7 +1179,11 @@ RefPtr<DrawingBuffer::ColorBuffer> DrawingBuffer::CreateColorBuffer(
       buffer_format = gfx::BufferFormat::RGBA_8888;
       gl_format = GL_RGBA;
     } else {
-      buffer_format = gfx::BufferFormat::BGRX_8888;
+      buffer_format = gfx::BufferFormat::RGBX_8888;
+      if (gpu::IsImageFromGpuMemoryBufferFormatSupported(
+              gfx::BufferFormat::BGRX_8888,
+              ContextProvider()->GetCapabilities()))
+        buffer_format = gfx::BufferFormat::BGRX_8888;
       gl_format = GL_RGB;
     }
     gpu_memory_buffer = gpu_memory_buffer_manager->CreateGpuMemoryBuffer(