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

cc/tiles/image_manager.cc

Index: cc/tiles/image_manager.cc
diff --git a/cc/tiles/image_manager.cc b/cc/tiles/image_manager.cc
index cb11e9ec19266ae01c1577b07fb3b2dfe7e13996..c9c40f060673aac8e660793debcff1f5685147e2 100644
--- a/cc/tiles/image_manager.cc
+++ b/cc/tiles/image_manager.cc
@@ -10,6 +10,10 @@ ImageManager::ImageManager() = default;
 ImageManager::~ImageManager() = default;
 
 void ImageManager::SetImageDecodeController(ImageDecodeController* controller) {
+  if (!controller_) {
+    SetPredecodeImages(std::vector<DrawImage>(),

[enne (OOO), 2016/09/16 17:45:44]

Why do you need to do this? Why would there be locked images before an image
controller is set? (Or why wouldn't you do this when the image decode controller
changed vs is set for the first time?)

Do you mean controller and not controller_?

[vmpstr, 2016/09/16 18:11:49]

Errr, yeah I meant controller here. I've added a test for this.

+                       ImageDecodeController::TracingInfo());
+  }
   controller_ = controller;
 }
 
@@ -43,4 +47,14 @@ void ImageManager::ReduceMemoryUsage() {
   controller_->ReduceCacheUsage();
 }
 
+std::vector<scoped_refptr<TileTask>> ImageManager::SetPredecodeImages(
+    std::vector<DrawImage> images,
+    const ImageDecodeController::TracingInfo& tracing_info) {
+  std::vector<scoped_refptr<TileTask>> new_tasks;
+  GetTasksForImagesAndRef(&images, &new_tasks, tracing_info);
+  UnrefImages(predecode_locked_images_);
+  predecode_locked_images_ = std::move(images);
+  return new_tasks;
+}
+
 }  // namespace cc