Use preferred format to allocate memory for decoded images

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 5e21974d5802a02a71f1ebf7b93e3040112d56d3..dd7bd235b3cfca87ec67661c03bef8ed14c76d0c 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -2145,7 +2145,8 @@ void LayerTreeHostImpl::CreateTileManagerResources() {
     image_decode_controller_ = make_scoped_ptr(new GpuImageDecodeController);
   } else {
     image_decode_controller_ =
-        make_scoped_ptr(new SoftwareImageDecodeController);
+        make_scoped_ptr(new SoftwareImageDecodeController(
+            settings_.renderer_settings.preferred_tile_format));

[reveman, 2016/03/16 14:53:35]

What if preferred_tile_format is a compressed format? e.g. ETC1.
(--enable-tile-compression)

Maybe add an utility function to software_image_decode_controller.cc that
returns SkColorType to use for images based on a resource format instead of
using ResourceFormatToSkColorType directly.

[bashi, 2016/03/17 01:52:14]

I didn't notice that. Done.

   }
 
   // TODO(vmpstr): Initialize tile task limit at ctor time.