cc: Devirtualize DisplayItem::ExternalMemoryUsage().

cc/playback/clip_path_display_item.h

Index: cc/playback/clip_path_display_item.h
diff --git a/cc/playback/clip_path_display_item.h b/cc/playback/clip_path_display_item.h
index e1eccd8298576d5a88f5441b52031889fa46f7da..f8ea8ab6e11bbe8982d3b4f45891d2388ee8db7c 100644
--- a/cc/playback/clip_path_display_item.h
+++ b/cc/playback/clip_path_display_item.h
@@ -30,8 +30,12 @@ class CC_EXPORT ClipPathDisplayItem : public DisplayItem {
               SkPicture::AbortCallback* callback) const override;
   void AsValueInto(const gfx::Rect& visual_rect,
                    base::trace_event::TracedValue* array) const override;
-  size_t ExternalMemoryUsage() const override;
 
+  size_t ExternalMemoryUsage() const {
+    // The size of SkPath's external storage is not currently accounted for (and
+    // may well be shared anyway).
+    return 0;
+  }
   int ApproximateOpCount() const { return 1; }
 
  private:
@@ -57,7 +61,6 @@ class CC_EXPORT EndClipPathDisplayItem : public DisplayItem {
               SkPicture::AbortCallback* callback) const override;
   void AsValueInto(const gfx::Rect& visual_rect,
                    base::trace_event::TracedValue* array) const override;
-  size_t ExternalMemoryUsage() const override;
 
   int ApproximateOpCount() const { return 0; }
 };