cc: Unittest for checking already failed image decode task.

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 "base/memory/discardable_memory_allocator.h"
 #include "base/memory/ptr_util.h"
 #include "base/numerics/safe_math.h"
 #include "base/strings/stringprintf.h"
@@ skipping 803 matching lines @@
   images_pending_deletion_.clear();
 }
 
 SkImageInfo GpuImageDecodeController::CreateImageInfoForDrawImage(
     const DrawImage& draw_image) const {
   return SkImageInfo::Make(
       draw_image.image()->width(), draw_image.image()->height(),
       ResourceFormatToClosestSkColorType(format_), kPremul_SkAlphaType);
 }
 
+void GpuImageDecodeController::SetImageDecodingFailedForTesting(
+    const DrawImage& image) {
+  base::AutoLock lock(lock_);
+  auto found = image_data_.Peek(image.image()->uniqueID());
+  DCHECK(found != image_data_.end());
+  ImageData* image_data = found->second.get();
+  image_data->decode.decode_failure = true;
+}
+
 }  // namespace cc