Revert of Back PaintRecord with PaintOpBuffer instead of SkPicture

third_party/WebKit/Source/platform/graphics/paint/CompositingRecorder.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/CompositingRecorder.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/CompositingRecorder.cpp b/third_party/WebKit/Source/platform/graphics/paint/CompositingRecorder.cpp
index 7eac3491469a701ff97a3110d0bd6afd24a29725..cdcd8fd07f413cf43f16af7211cc5f8df50797f1 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/CompositingRecorder.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/CompositingRecorder.cpp
@@ -29,8 +29,58 @@
 CompositingRecorder::~CompositingRecorder() {
   if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
     return;
-  graphics_context_.GetPaintController().EndItem<EndCompositingDisplayItem>(
-      client_);
+  // If the end of the current display list is of the form
+  // [BeginCompositingDisplayItem] [DrawingDisplayItem], then fold the
+  // BeginCompositingDisplayItem into a new DrawingDisplayItem that replaces
+  // them both. This allows Skia to optimize for the case when the
+  // BeginCompositingDisplayItem represents a simple opacity/color that can be
+  // merged into the opacity/color of the drawing. See crbug.com/628831 for more
+  // details.
+  PaintController& paint_controller = graphics_context_.GetPaintController();
+  const DisplayItem* last_display_item = paint_controller.LastDisplayItem(0);
+  const DisplayItem* second_to_last_display_item =
+      paint_controller.LastDisplayItem(1);
+  // TODO(chrishtr): remove the call to LastDisplayItemIsSubsequenceEnd when
+  // https://codereview.chromium.org/2768143002 lands.
+  if (!RuntimeEnabledFeatures::slimmingPaintV2Enabled() && last_display_item &&
+      second_to_last_display_item && last_display_item->DrawsContent() &&
+      second_to_last_display_item->GetType() ==
+          DisplayItem::kBeginCompositing &&
+      !paint_controller.LastDisplayItemIsSubsequenceEnd()) {
+    FloatRect cull_rect(
+        ((DrawingDisplayItem*)last_display_item)->GetPaintRecord()->cullRect());
+    const DisplayItemClient& display_item_client = last_display_item->Client();
+    DisplayItem::Type display_item_type = last_display_item->GetType();
+
+    // Re-record the last two DisplayItems into a new drawing. The new item
+    // cannot be cached, because it is a mutation of the DisplayItem the client
+    // thought it was painting.
+    paint_controller.BeginSkippingCache();
+    {
+#if DCHECK_IS_ON()
+      // In the recorder's scope we remove the last two display items which
+      // are combined into a new drawing.
+      DisableListModificationCheck disabler;
+#endif
+      DrawingRecorder new_recorder(graphics_context_, display_item_client,
+                                   display_item_type, cull_rect);
+      DCHECK(!DrawingRecorder::UseCachedDrawingIfPossible(
+          graphics_context_, display_item_client, display_item_type));
+
+      second_to_last_display_item->Replay(graphics_context_);
+      last_display_item->Replay(graphics_context_);
+      EndCompositingDisplayItem(client_).Replay(graphics_context_);
+
+      // Remove the DrawingDisplayItem.
+      paint_controller.RemoveLastDisplayItem();
+      // Remove the BeginCompositingDisplayItem.
+      paint_controller.RemoveLastDisplayItem();
+    }
+    paint_controller.EndSkippingCache();
+  } else {
+    graphics_context_.GetPaintController().EndItem<EndCompositingDisplayItem>(
+        client_);
+  }
 }
 
 }  // namespace blink