AVDACodecImages keep their backing SurfaceTexture alive

gpu/command_buffer/service/texture_manager.cc

 // Copyright (c) 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 "gpu/command_buffer/service/texture_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1469 matching lines @@
   DCHECK_GE(level, 0);
   size_t face_index = GLES2Util::GLTargetToFaceIndex(target);
   DCHECK_LT(static_cast<size_t>(face_index),
             face_infos_.size());
   DCHECK_LT(static_cast<size_t>(level),
             face_infos_[face_index].level_infos.size());
   Texture::LevelInfo& info =
       face_infos_[face_index].level_infos[level];
   DCHECK_EQ(info.target, target);
   DCHECK_EQ(info.level, level);
+  bool image_previously_bound = !!info.image;
   info.image = image;
   info.stream_texture_image = stream_texture_image;
   info.image_state = state;
 
+
+  // Clear the unowned service id because the previous image might own it, in
+  // which case it's no longer valid.
+  if (image_previously_bound && level == 0)

[liberato (no reviews please), 2016/05/26 16:59:19]

i don't think that one needs to check if an image was previously bound, or even
(probably) the level.

AVDA can set them in the right order.

also, please add documentation to texture_manager.h::SetUnownedServiceId that
it's cleared on any SetLevelImage.  else it'll confuse somebody (probably us :)
) some day.

the texture_manager changes can probably be a separate CL.  it looks like AVDA
does the SetLevel / SetUnowned calls in the right order already.  i think that
they stand on their own as a security improvement.

+    SetUnownedServiceId(0);
+
   UpdateCanRenderCondition();
   UpdateHasImages();
   UpdateEmulatingRGB();
 }
 
 void Texture::SetLevelImage(GLenum target,
                             GLint level,
                             gl::GLImage* image,
                             ImageState state) {
   SetLevelImageInternal(target, level, image, nullptr, state);
@@ skipping 1805 matching lines @@
 uint32_t TextureManager::GetServiceIdGeneration() const {
   return current_service_id_generation_;
 }
 
 void TextureManager::IncrementServiceIdGeneration() {
   current_service_id_generation_++;
 }
 
 }  // namespace gles2
 }  // namespace gpu