Implements core logic for Pixel Canvas

cc/paint/display_item_list.h

Index: cc/paint/display_item_list.h
diff --git a/cc/paint/display_item_list.h b/cc/paint/display_item_list.h
index a115c9017da8167ae626e53e1e58127f220bcf7a..b22d0396d2a95803ab19d7feb99f6cffebe81c09 100644
--- a/cc/paint/display_item_list.h
+++ b/cc/paint/display_item_list.h
@@ -142,6 +142,9 @@ class CC_PAINT_EXPORT DisplayItemList
   // an empty state.
   sk_sp<PaintRecord> ReleaseAsRecord();
 
+  bool pixel_canvas_enabled() const { return pixel_canvas_enabled_; }
+  void set_pixel_canvas_enabled(bool value) { pixel_canvas_enabled_ = value; }
+
  private:
   FRIEND_TEST_ALL_PREFIXES(DisplayItemListTest, AsValueWithNoOps);
   FRIEND_TEST_ALL_PREFIXES(DisplayItemListTest, AsValueWithOps);
@@ -185,6 +188,11 @@ class CC_PAINT_EXPORT DisplayItemList
   // Finalize().
   bool retain_visual_rects_ = false;
 
+  // Set true if we are using pixel canvas. This mode allows us to records all
+  // canvas draw commands in pixel aligned measurements and scale elements using
+  // the corner points.
+  bool pixel_canvas_enabled_ = false;
+
   friend class base::RefCountedThreadSafe<DisplayItemList>;
   FRIEND_TEST_ALL_PREFIXES(DisplayItemListTest, BytesUsed);
   DISALLOW_COPY_AND_ASSIGN(DisplayItemList);