Serialize DisplayListRecordingSource to protos.

cc/test/fake_content_layer_client.h

Index: cc/test/fake_content_layer_client.h
diff --git a/cc/test/fake_content_layer_client.h b/cc/test/fake_content_layer_client.h
index 00d562d2c140e3beb5e140ff40667a27fe3178e9..c63f5d2bc7045a888705402647df3e5584e68321 100644
--- a/cc/test/fake_content_layer_client.h
+++ b/cc/test/fake_content_layer_client.h
@@ -44,6 +44,10 @@ class FakeContentLayerClient : public ContentLayerClient {
   bool FillsBoundsCompletely() const override;
   size_t GetApproximateUnsharedMemoryUsage() const override;
 
+  void set_display_list_use_cached_picture(bool use_cached_picture) {
+    display_list_use_cached_picture_ = use_cached_picture;
+  }
+
   void set_fill_with_nonsolid_color(bool nonsolid) {
     fill_with_nonsolid_color_ = nonsolid;
   }
@@ -89,6 +93,7 @@ class FakeContentLayerClient : public ContentLayerClient {
   typedef std::vector<std::pair<gfx::RectF, SkPaint>> RectPaintVector;
   typedef std::vector<ImageData> ImageVector;
 
+  bool display_list_use_cached_picture_;
   bool fill_with_nonsolid_color_;
   RectPaintVector draw_rects_;
   ImageVector draw_images_;