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..2b08c2d8e4262df0901b4c524fa7c7ca2c54c3a9 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) {

[enne (OOO), 2016/09/16 18:21:37]

Sure, but do you also need to do this when the image controller changes as well?
If it goes non-null => non-null?

[vmpstr, 2016/09/16 18:38:49]

Well... I mean I can add a DCHECK, but normally if it switches from non-null to
non-null, it's too late to do anything with the old controller because it's
already been deleted. Tile manager can't get SetResources twice without getting
a FinishTasksAndCleanUp in between.

+    SetPredecodeImages(std::vector<DrawImage>(),
+                       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