Expose the number of top-level PaintOps held in a PaintRecorder.

Bug: 973801
Change-Id: I90c5eb4f4bd84e0ac822ae0d15b3d730e769306e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2199178
Commit-Queue: Caleb Raitto <caraitto@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#768626}

cc/paint/display_item_list.h

@@ -181,6 +181,9 @@ class CC_PAINT_EXPORT DisplayItemList
   std::string ToString() const;
   bool has_draw_ops() const { return paint_op_buffer_.has_draw_ops(); }
 
+  // Ops with nested paint ops are considered as a single op.
+  size_t num_paint_ops() const { return paint_op_buffer_.size(); }
+
  private:
   friend class DisplayItemListTest;
   friend gpu::raster::RasterImplementation;

cc/paint/paint_recorder.cc

@@ -51,4 +51,8 @@ bool PaintRecorder::ListHasDrawOps() const {
   return display_item_list_->has_draw_ops();
 }
 
+size_t PaintRecorder::num_paint_ops() const {
+  return display_item_list_->num_paint_ops();
+}
+
 }  // namespace cc

cc/paint/paint_recorder.h

@@ -39,6 +39,9 @@ class CC_PAINT_EXPORT PaintRecorder {
 
   bool ListHasDrawOps() const;
 
+  // Ops with nested paint ops are considered as a single op.
+  size_t num_paint_ops() const;
+
  protected:
   virtual std::unique_ptr<RecordPaintCanvas> CreateCanvas(DisplayItemList* list,
                                                           const SkRect& bounds);