Use IDCompositionSurface to implement DirectCompositionSurfaceWin.

cc/output/direct_renderer.h

Index: cc/output/direct_renderer.h
diff --git a/cc/output/direct_renderer.h b/cc/output/direct_renderer.h
index c7a0b5e43f452c578cb355aa10fae67848e46940..ff298fcb104425c8a7115c253f9088124954eceb 100644
--- a/cc/output/direct_renderer.h
+++ b/cc/output/direct_renderer.h
@@ -176,12 +176,15 @@ class CC_EXPORT DirectRenderer {
 
   // Whether it's valid to SwapBuffers with an empty rect. Trivially true when
   // using partial swap.
-  bool allow_empty_swap_;
+  bool allow_empty_swap_ = false;
   // Whether partial swap can be used.
-  bool use_partial_swap_;
+  bool use_partial_swap_ = false;
   // Whether overdraw feedback is enabled and can be used.
   bool overdraw_feedback_ = false;
 

[danakj, 2017/02/15 16:01:01]

nit: no whitespace

+  // Whether the SetDrawRectangle command is in use.
+  bool use_set_draw_rectangle_ = false;
+
   // TODO(danakj): Just use a vector of pairs here? Hash map is way overkill.
   std::unordered_map<int, std::unique_ptr<ScopedResource>>
       render_pass_textures_;