Remove optimization-blocking code.

cc/tiles/gpu_image_decode_controller.cc

 // Copyright 2016 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/tiles/gpu_image_decode_controller.h"
 
 #include <inttypes.h>
 
 #include "base/debug/alias.h"
 #include "base/memory/discardable_memory_allocator.h"
@@ skipping 925 matching lines @@
     return;
   }
 
   TRACE_EVENT0("cc", "GpuImageDecodeController::DecodeImage");
 
   image_data->decode.ResetData();
   std::unique_ptr<base::DiscardableMemory> backing_memory;
   {
     base::AutoUnlock unlock(lock_);
 
-    size_t image_data_size = image_data->size;
-    base::debug::Alias(&image_data_size);
     backing_memory = base::DiscardableMemoryAllocator::GetInstance()
-                         ->AllocateLockedDiscardableMemory(image_data_size);
+                         ->AllocateLockedDiscardableMemory(image_data->size);
 
     switch (image_data->mode) {
       case DecodedDataMode::CPU: {
         SkImageInfo image_info = CreateImageInfoForDrawImage(
             draw_image, image_data->upload_scale_mip_level);
         // In order to match GPU scaling quality (which uses mip-maps at high
         // quality), we want to use at most medium filter quality for the
         // scale.
         SkPixmap image_pixmap(image_info, backing_memory->data(),
                               image_info.minRowBytes());
@@ skipping 220 matching lines @@
       // TODO(tasak): free this component's caches as much as possible before
       // suspending renderer.
       break;
     case base::MemoryState::UNKNOWN:
       // NOT_REACHED.
       break;
   }
 }
 
 }  // namespace cc