cc: Remove the base RasterSource

cc/layers/picture_layer.cc

Index: cc/layers/picture_layer.cc
diff --git a/cc/layers/picture_layer.cc b/cc/layers/picture_layer.cc
index d92ccc1dfa6a716e12c0ef81b5fea3e80ff2a983..81ae0b12a0143056103aae72bc6452c007b566b7 100644
--- a/cc/layers/picture_layer.cc
+++ b/cc/layers/picture_layer.cc
@@ -74,7 +74,7 @@ void PictureLayer::PushPropertiesTo(LayerImpl* base_layer) {
 
   // Preserve lcd text settings from the current raster source.
   bool can_use_lcd_text = layer_impl->RasterSourceUsesLCDText();
-  scoped_refptr<RasterSource> raster_source =
+  scoped_refptr<DisplayListRasterSource> raster_source =
       recording_source_->CreateRasterSource(can_use_lcd_text);
   layer_impl->set_gpu_raster_max_texture_size(
       layer_tree_host()->device_viewport_size());
@@ -183,7 +183,7 @@ skia::RefPtr<SkPicture> PictureLayer::GetPicture() const {
       client_, &recording_invalidation, layer_size, gfx::Rect(layer_size),
       update_source_frame_number_, DisplayListRecordingSource::RECORD_NORMALLY);
 
-  scoped_refptr<RasterSource> raster_source =
+  scoped_refptr<DisplayListRasterSource> raster_source =
       recording_source->CreateRasterSource(false);
 
   return raster_source->GetFlattenedPicture();