Chromium implementation of discardBackbuffer WebGraphicsContext3D extension.

content/common/gpu/texture_image_transport_surface.cc

Index: content/common/gpu/texture_image_transport_surface.cc
diff --git a/content/common/gpu/texture_image_transport_surface.cc b/content/common/gpu/texture_image_transport_surface.cc
index aad677ad142e73993068def7c2f8dc1cdabff101..38417aeadde3b7b53afcec13ebf950ed35792b4f 100644
--- a/content/common/gpu/texture_image_transport_surface.cc
+++ b/content/common/gpu/texture_image_transport_surface.cc
@@ -157,9 +157,7 @@ void TextureImageTransportSurface::SetBufferAllocation(
       break;
     case BUFFER_ALLOCATION_FRONT_ONLY:
     case BUFFER_ALLOCATION_NONE:
-      // TODO(piman): Re-enable this (or something else) when we fix the
-      // renderer so it doesn't try to draw/swap on deleted back buffers.
-      // ReleaseBackTexture();
+      ReleaseBackTexture();
       break;
   };
 }
@@ -195,6 +193,8 @@ bool TextureImageTransportSurface::SwapBuffers() {
   front_ = back();
   previous_damage_rect_ = gfx::Rect(textures_[front_].size);
 
+  DCHECK(textures_[front_].client_id != 0);
+
   GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params params;
   params.surface_handle = textures_[front_].client_id;
   helper_->SendAcceleratedSurfaceBuffersSwapped(params);