Correct DisplayItemList::ApproximateOpCount() for flattened picture

cc/playback/display_item_list_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/playback/display_item_list.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 523 matching lines @@
 
   // A single DrawingDisplayItem with a large AA concave path shouldn't trigger
   // a veto.
   EXPECT_TRUE(list->IsSuitableForGpuRasterization());
 
   // Now check the RasterIntoCanvas path.
   list = DisplayItemList::Create(layer_rect, settings);
   DrawingDisplayItem suitable_item(suitable_picture);
   list->RasterIntoCanvas(suitable_item);
   list->Finalize();
+  EXPECT_TRUE(list->ApproximateOpCount());
   EXPECT_TRUE(list->IsSuitableForGpuRasterization());
 
   list = DisplayItemList::Create(layer_rect, settings);
   canvas = sk_ref_sp(recorder.beginRecording(gfx::RectToSkRect(layer_rect)));
   for (int i = 0; i < 10; ++i)
     canvas->drawPath(path, paint);
   sk_sp<SkPicture> unsuitable_picture = recorder.finishRecordingAsPicture();
   list->CreateAndAppendItem<DrawingDisplayItem>(kVisualRect,
                                                 unsuitable_picture);
   list->Finalize();
@@ skipping 191 matching lines @@
 
   value = list->AsValue(false)->ToString();
   EXPECT_EQ(value.find("\"items\":"), std::string::npos);
   EXPECT_NE(value.find("\"layer_rect\":[0,0,0,0]"), std::string::npos);
   // There should be no skp64 entry present as the items aren't included and the
   // layer rect is empty.
   EXPECT_EQ(value.find("\"skp64\":"), std::string::npos);
 }
 
 }  // namespace cc