cc: Move (partially) the predecode image tracking to ImageManager.

cc/tiles/image_manager_unittest.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/image_decode_controller.h"
+#include "cc/tiles/image_manager.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cc {
+
+class TestableController : public ImageDecodeController {
+ public:
+  bool GetTaskForImageAndRef(const DrawImage& image,
+                             const TracingInfo& tracing_info,
+                             scoped_refptr<TileTask>* task) override {
+    *task = nullptr;
+    ++number_of_refs_;
+    return true;
+  }
+
+  void UnrefImage(const DrawImage& image) override {
+    ASSERT_GT(number_of_refs_, 0);
+    --number_of_refs_;
+  }
+  DecodedDrawImage GetDecodedImageForDraw(const DrawImage& image) override {
+    return DecodedDrawImage(nullptr, kNone_SkFilterQuality);
+  }
+  void DrawWithImageFinished(const DrawImage& image,
+                             const DecodedDrawImage& decoded_image) override {}
+  void ReduceCacheUsage() override {}
+  void SetShouldAggressivelyFreeResources(
+      bool aggressively_free_resources) override {}
+
+  int number_of_refs() const { return number_of_refs_; }
+
+ private:
+  int number_of_refs_ = 0;
+};
+
+TEST(ImageManagerTest, NullControllerUnrefsImages) {
+  TestableController controller;
+  ImageManager manager;
+  manager.SetImageDecodeController(&controller);
+
+  std::vector<DrawImage> images(10);
+  ImageDecodeController::TracingInfo tracing_info;
+
+  ASSERT_EQ(10u, images.size());
+  auto tasks = manager.SetPredecodeImages(std::move(images), tracing_info);
+  EXPECT_EQ(0u, tasks.size());
+  EXPECT_EQ(10, controller.number_of_refs());
+
+  manager.SetImageDecodeController(nullptr);
+  EXPECT_EQ(0, controller.number_of_refs());
+}
+
+}  // namespace cc