ResourceProvider should be able to avoid allocating immutable textures.

cc/output/gl_renderer.cc

Index: cc/output/gl_renderer.cc
diff --git a/cc/output/gl_renderer.cc b/cc/output/gl_renderer.cc
index ea2d2b57288068b45ca5e6e6ba6618611355be53..10014f8b89d9ab4d1fb9805210e8ac5176652a2a 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -616,9 +616,13 @@ scoped_ptr<ScopedResource> GLRenderer::DrawBackgroundFilters(
 
   scoped_ptr<ScopedResource> device_background_texture =
       ScopedResource::create(resource_provider_);
-  if (!device_background_texture->Allocate(window_rect.size(),
-                                           ResourceProvider::TextureUsageAny,
-                                           RGBA_8888)) {
+  // The TextureUsageFramebuffer hint makes ResourceProvider avoid immutable
+  // storage allocation (texStorage2DEXT) for this texture. copyTexImage2D fails
+  // when called on a texture having immutable storage.
+  if (!device_background_texture->Allocate(
+           window_rect.size(),
+           ResourceProvider::TextureUsageFramebuffer,
+           RGBA_8888)) {
     return scoped_ptr<ScopedResource>();
   } else {
     ResourceProvider::ScopedWriteLockGL lock(resource_provider_,