cc: Move pre-decodes to background worker.

cc/tiles/tile_manager_unittest.cc

Index: cc/tiles/tile_manager_unittest.cc
diff --git a/cc/tiles/tile_manager_unittest.cc b/cc/tiles/tile_manager_unittest.cc
index d36a7824fe3f6cb1e97cf3045951b71e62a4d1af..0584bb7a0ca39dce85c44822909ff291b3c9b967 100644
--- a/cc/tiles/tile_manager_unittest.cc
+++ b/cc/tiles/tile_manager_unittest.cc
@@ -2527,6 +2527,11 @@ TEST_F(CheckerImagingTileManagerTest, BuildsImageDecodeQueueAsExpected) {
       gfx::Rect(rect_to_raster));  // Eventually rect.
   host_impl()->tile_manager()->PrepareTiles(host_impl()->global_tile_state());
 
+  // Finish all raster and dispatch completion callback so that the decode work
+  // for checkered images can be scheduled.
+  static_cast<SynchronousTaskGraphRunner*>(task_graph_runner())->RunUntilIdle();
+  base::RunLoop().RunUntilIdle();
+
   // Run decode tasks to trigger completion of any pending decodes.
   FlushDecodeTasks();
 
@@ -2636,6 +2641,11 @@ TEST_F(CheckerImagingTileManagerMemoryTest, AddsAllNowTilesToImageDecodeQueue) {
       complete_tiling_rect);  // Eventually rect.
   host_impl()->tile_manager()->PrepareTiles(host_impl()->global_tile_state());
 
+  // Finish all raster work so the decode work for checkered images can be
+  // scheduled.
+  static_cast<SynchronousTaskGraphRunner*>(task_graph_runner())->RunUntilIdle();
+  base::RunLoop().RunUntilIdle();
+
   // Flush all decode tasks. The tiles with checkered images should be
   // invalidated.
   FlushDecodeTasks();