cc: Make image controller return a status with the callback.

cc/tiles/checker_image_tracker.cc

Index: cc/tiles/checker_image_tracker.cc
diff --git a/cc/tiles/checker_image_tracker.cc b/cc/tiles/checker_image_tracker.cc
index c081132e6ece23c5e9569af2dc37968d9e69e5cb..c8113d4d56052edb486948d64999a2680ce952d8 100644
--- a/cc/tiles/checker_image_tracker.cc
+++ b/cc/tiles/checker_image_tracker.cc
@@ -77,10 +77,12 @@ void CheckerImageTracker::DidActivateSyncTree() {
 
 void CheckerImageTracker::DidFinishImageDecode(
     ImageId image_id,
-    ImageController::ImageDecodeRequestId request_id) {
+    ImageController::ImageDecodeRequestId request_id,
+    ImageController::ImageDecodeResult result) {
   TRACE_EVENT_ASYNC_END0("cc", "CheckerImageTracker::DeferImageDecode",
                          image_id);
 
+  DCHECK_NE(result, ImageController::ImageDecodeResult::DECODE_NOT_REQUIRED);
   DCHECK_NE(pending_image_decodes_.count(image_id), 0u);
   pending_image_decodes_.erase(image_id);