cc: Devirtualize DisplayItem::ExternalMemoryUsage().

cc/playback/filter_display_item.h

Index: cc/playback/filter_display_item.h
diff --git a/cc/playback/filter_display_item.h b/cc/playback/filter_display_item.h
index b4ba8cedcc14e8dbc2460699b090c9195b4ca8fa..499d05bb53a4bc4634e16e1bf2d890060a3724ac 100644
--- a/cc/playback/filter_display_item.h
+++ b/cc/playback/filter_display_item.h
@@ -32,8 +32,12 @@ class CC_EXPORT FilterDisplayItem : 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 {
+    // FilterOperations doesn't expose its capacity, but size is probably good
+    // enough.
+    return filters_.size() * sizeof(filters_.at(0));
+  }
   int ApproximateOpCount() const { return 1; }
 
  private:
@@ -61,7 +65,6 @@ class CC_EXPORT EndFilterDisplayItem : 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; }
 };