Skip paint chunks with effectively invisible opacity.

third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp

 // 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 "core/paint/PaintLayerPainter.h"
 
 #include "core/frame/LocalFrame.h"
 #include "core/layout/LayoutView.h"
 #include "core/paint/ClipPathClipper.h"
 #include "core/paint/FilterPainter.h"
@@ skipping 59 matching lines @@
   if (layout_object.HasBackdropFilter())
     return false;
 
   // Always paint when 'will-change: opacity' is present. Reduces jank for
   // common animation implementation approaches, for example, an element that
   // starts with opacity zero and later begins to animate.
   if (layout_object.StyleRef().HasWillChangeOpacityHint())
     return false;
 
   if (RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
-    if (layout_object.StyleRef().Opacity())
-      return false;
-
+    const ObjectPaintProperties* properties = layout_object.PaintProperties();
     const EffectPaintPropertyNode* effect =
-        layout_object.PaintProperties()->Effect();
+        properties ? properties->Effect() : nullptr;
     if (effect && effect->RequiresCompositingForAnimation()) {
       return false;
     }
   }
 
   // 0.0004f < 1/2048. With 10-bit color channels (only available on the
   // newest Macs; otherwise it's 8-bit), we see that an alpha of 1/2048 or
   // less leads to a color output of less than 0.5 in all channels, hence
   // not visible.
   static const float kMinimumVisibleOpacity = 0.0004f;
   if (paint_layer_.PaintsWithTransparency(
-          painting_info.GetGlobalPaintFlags())) {
-    if (layout_object.StyleRef().Opacity() < kMinimumVisibleOpacity) {
-      return true;
-    }
-  }
+          painting_info.GetGlobalPaintFlags()) &&
+      layout_object.StyleRef().Opacity() < kMinimumVisibleOpacity)
+    return true;
   return false;
 }
 
 PaintResult PaintLayerPainter::Paint(
     GraphicsContext& context,
     const PaintLayerPaintingInfo& painting_info,
     PaintLayerFlags paint_flags) {
   // https://code.google.com/p/chromium/issues/detail?id=343772
   DisableCompositingQueryAsserts disabler;
 
@@ skipping 1130 matching lines @@
           context, layout_object, kPaintPhaseClippingMask))
     return;
 
   IntRect snapped_clip_rect = PixelSnappedIntRect(clip_rect.Rect());
   LayoutObjectDrawingRecorder drawing_recorder(
       context, layout_object, kPaintPhaseClippingMask, snapped_clip_rect);
   context.FillRect(snapped_clip_rect, Color::kBlack);
 }
 
 }  // namespace blink