Revert of cc: Shrink size of display item

cc/playback/display_item_list.h

 // 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.
 
 #ifndef CC_PLAYBACK_DISPLAY_ITEM_LIST_H_
 #define CC_PLAYBACK_DISPLAY_ITEM_LIST_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/base/cc_export.h"
 #include "cc/base/contiguous_container.h"
 #include "cc/playback/discardable_image_map.h"
 #include "cc/playback/display_item.h"
 #include "cc/playback/display_item_list_settings.h"
 #include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "ui/gfx/geometry/rect.h"
 
 class SkCanvas;
 class SkPictureRecorder;
 
 namespace cc {
-class DisplayItem;
-class DrawingDisplayItem;
 
 namespace proto {
 class DisplayItemList;
 }
 
 class CC_EXPORT DisplayItemList
     : public base::RefCountedThreadSafe<DisplayItemList> {
  public:
   // Creates a display item list. If picture caching is used, then layer_rect
   // specifies the cull rect of the display item list (the picture will not
@@ skipping 18 matching lines @@
   void Raster(SkCanvas* canvas,
               SkPicture::AbortCallback* callback,
               const gfx::Rect& canvas_target_playback_rect,
               float contents_scale) const;
 
   // This is a fast path for use only if canvas_ is set and
   // retain_individual_display_items_ is false. This method also updates
   // is_suitable_for_gpu_rasterization_ and approximate_op_count_.
   void RasterIntoCanvas(const DisplayItem& display_item);
 
-  // Because processing happens in this function, all the set up for
-  // this item should be done via the args, which is why the return
-  // type needs to be const, to prevent set-after-processing mistakes.
-  template <typename DisplayItemType, typename... Args>
-  const DisplayItemType& CreateAndAppendItem(const gfx::Rect& visual_rect,
-                                             const Args&... args) {
+  template <typename DisplayItemType>
+  DisplayItemType* CreateAndAppendItem(const gfx::Rect& visual_rect) {
+#if DCHECK_IS_ON()
+    needs_process_ = true;
+#endif
     visual_rects_.push_back(visual_rect);
-    // TODO(enne): This should forward the args.
-    auto* item = &items_.AllocateAndConstruct<DisplayItemType>(args...);
-    approximate_op_count_ += item->ApproximateOpCount();
-    // TODO(crbug.com/513016): None of the items might individually trigger a
-    // veto even though they collectively have enough "bad" operations that a
-    // corresponding flattened Picture would get vetoed.
-    is_suitable_for_gpu_rasterization_ &= item->IsSuitableForGpuRasterization();
-    ProcessAppendedItem(item);
-    return *item;
+    ProcessAppendedItemsOnTheFly();
+    return &items_.AllocateAndConstruct<DisplayItemType>();
   }
 
+  // Removes the last item. This cannot be called on lists with cached pictures
+  // (since the data may already have been incorporated into cached picture
+  // sizes, etc).
+  void RemoveLast();
+
   // Called after all items are appended, to process the items and, if
   // applicable, create an internally cached SkPicture.
   void Finalize();
 
   bool IsSuitableForGpuRasterization() const;
   int ApproximateOpCount() const;
   size_t ApproximateMemoryUsage() const;
   bool ShouldBeAnalyzedForSolidColor() const;
 
   bool RetainsIndividualDisplayItems() const;
 
   scoped_refptr<base::trace_event::ConvertableToTraceFormat> AsValue(
       bool include_items) const;
 
   void EmitTraceSnapshot() const;
 
   void GenerateDiscardableImagesMetadata();
   void GetDiscardableImagesInRect(const gfx::Rect& rect,
                                   float raster_scale,
                                   std::vector<DrawImage>* images);
 
   gfx::Rect VisualRectForTesting(int index) { return visual_rects_[index]; }
 
  private:
   DisplayItemList(gfx::Rect layer_rect,
                   const DisplayItemListSettings& display_list_settings,
                   bool retain_individual_display_items);
   ~DisplayItemList();
 
-  void ProcessAppendedItem(const DisplayItem* item);
+  // While appending new items, if they are not being retained, this can process
+  // periodically to avoid retaining all the items and processing at the end.
+  void ProcessAppendedItemsOnTheFly();
+  void ProcessAppendedItems();
+#if DCHECK_IS_ON()
+  bool ProcessAppendedItemsCalled() const { return !needs_process_; }
+  bool needs_process_;
+#else
+  bool ProcessAppendedItemsCalled() const { return true; }
+#endif
 
   ContiguousContainer<DisplayItem> items_;
   // The visual rects associated with each of the display items in the
   // display item list. There is one rect per display item, and the
   // position in |visual_rects_| matches the position of the item in
   // |items_| . These rects are intentionally kept separate
   // because they are not needed while walking the |items_| for raster.
   std::vector<gfx::Rect> visual_rects_;
   skia::RefPtr<SkPicture> picture_;
 
   scoped_ptr<SkPictureRecorder> recorder_;
   skia::RefPtr<SkCanvas> canvas_;
   const DisplayItemListSettings settings_;
   bool retain_individual_display_items_;
 
   gfx::Rect layer_rect_;
   bool is_suitable_for_gpu_rasterization_;
   int approximate_op_count_;
 
   // Memory usage due to the cached SkPicture.
   size_t picture_memory_usage_;
 
+  // Memory usage due to external data held by display items.
+  size_t external_memory_usage_;
+
   DiscardableImageMap image_map_;
 
   friend class base::RefCountedThreadSafe<DisplayItemList>;
   FRIEND_TEST_ALL_PREFIXES(DisplayItemListTest, ApproximateMemoryUsage);
   DISALLOW_COPY_AND_ASSIGN(DisplayItemList);
 };
 
 }  // namespace cc
 
 #endif  // CC_PLAYBACK_DISPLAY_ITEM_LIST_H_