ResourceProvider should be able to avoid allocating immutable textures.

cc/resources/resource_provider.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/resources/resource_provider.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/containers/hash_tables.h"
@@ skipping 1674 matching lines @@
 
   DCHECK(resource->gl_id || resource->allocated);
   if (resource->allocated || !resource->gl_id)
     return;
   resource->allocated = true;
   WebGraphicsContext3D* context3d = Context3d();
   gfx::Size& size = resource->size;
   DCHECK_EQ(resource->target, static_cast<GLenum>(GL_TEXTURE_2D));
   ResourceFormat format = resource->format;
   GLC(context3d, context3d->bindTexture(GL_TEXTURE_2D, resource->gl_id));
-  if (use_texture_storage_ext_ && IsFormatSupportedForStorage(format)) {
+  if (use_texture_storage_ext_ && IsFormatSupportedForStorage(format) &&
+      resource->hint != TextureUsageFramebuffer) {
     GLenum storage_format = TextureToStorageFormat(format);
     GLC(context3d, context3d->texStorage2DEXT(GL_TEXTURE_2D,
                                               1,
                                               storage_format,
                                               size.width(),
                                               size.height()));
   } else {
     // ETC1 does not support preallocation.
     if (format != ETC1) {
       GLC(context3d,
@@ skipping 122 matching lines @@
   context->getIntegerv(GL_ACTIVE_TEXTURE, &active_unit);
   return active_unit;
 }
 
 blink::WebGraphicsContext3D* ResourceProvider::Context3d() const {
   ContextProvider* context_provider = output_surface_->context_provider();
   return context_provider ? context_provider->Context3d() : NULL;
 }
 
 }  // namespace cc