Implement native GMB backbuffers in the GLES2 Command Decoder.

gpu/command_buffer/tests/gl_manager.h

Index: gpu/command_buffer/tests/gl_manager.h
diff --git a/gpu/command_buffer/tests/gl_manager.h b/gpu/command_buffer/tests/gl_manager.h
index e4fdaafa186878ad77e27a4810ab1cead2e15820..6a45db4c52c58454188ce6468274b7612809728a 100644
--- a/gpu/command_buffer/tests/gl_manager.h
+++ b/gpu/command_buffer/tests/gl_manager.h
@@ -35,6 +35,7 @@ namespace gpu {
 
 class CommandBufferService;
 class CommandExecutor;
+class ImageFactory;
 class SyncPointClient;
 class SyncPointOrderData;
 class SyncPointManager;
@@ -77,6 +78,12 @@ class GLManager : private GpuControl {
     bool force_shader_name_hashing;
     // Whether the buffer is multisampled.
     bool multisampled;
+    // Whether the backbuffer has an alpha channel.
+    bool backbuffer_alpha;
+    // The ImageFactory to use to generate images for the backbuffer.
+    gpu::ImageFactory* image_factory;
+    // Enable the feature |arb_texture_rectangle|.
+    bool enable_arb_texture_rectangle;
   };
   GLManager();
   ~GLManager() override;