Fix crash in PaintOpBuffer alpha optimization

cc/paint/paint_op_buffer.cc

 // Copyright 2017 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/paint/paint_op_buffer.h"
 
 #include "cc/paint/display_item_list.h"
 #include "cc/paint/paint_record.h"
 #include "third_party/skia/include/core/SkAnnotation.h"
 
@@ skipping 102 matching lines @@
                      const SkMatrix& original_ctm) {
     op->Raster(canvas);
   }
   static void RasterWithAlpha(const DrawRecordOp* op,
                               SkCanvas* canvas,
                               uint8_t alpha) {
     // This "looking into records" optimization is done here instead of
     // in the PaintOpBuffer::Raster function as DisplayItemList calls
     // into RasterWithAlpha directly.
     if (op->record->approximateOpCount() == 1) {
-      op->record->GetFirstOp()->RasterWithAlpha(canvas, alpha);
-      return;
+      PaintOp* single_op = op->record->GetFirstOp();
+      // RasterWithAlpha only supported for draw ops.
+      if (single_op->IsDrawOp()) {
+        single_op->RasterWithAlpha(canvas, alpha);
+        return;
+      }
     }
 
     canvas->saveLayerAlpha(nullptr, alpha);
     op->Raster(canvas);
     canvas->restore();
   }
 };
 
 // TODO(enne): partially specialize RasterWithAlpha for draw color?
 
@@ skipping 216 matching lines @@
 }
 
 void PaintOp::Raster(SkCanvas* canvas, const SkMatrix& original_ctm) const {
   g_raster_functions[type](this, canvas, original_ctm);
 }
 
 void PaintOp::RasterWithAlpha(SkCanvas* canvas, uint8_t alpha) const {
   g_raster_alpha_functions[type](this, canvas, alpha);
 }
 
-DrawDisplayItemListOp::DrawDisplayItemListOp(
-    scoped_refptr<DisplayItemList> list)
-    : list(list) {}
-
-size_t DrawDisplayItemListOp::AdditionalBytesUsed() const {
-  return list->ApproximateMemoryUsage();
-}
-
 int ClipPathOp::CountSlowPaths() const {
   return antialias && !path.isConvex() ? 1 : 0;
 }
 
 int DrawLineOp::CountSlowPaths() const {
   if (const SkPathEffect* effect = flags.getPathEffect()) {
     SkPathEffect::DashInfo info;
     SkPathEffect::DashType dashType = effect->asADash(&info);
     if (flags.getStrokeCap() != PaintFlags::kRound_Cap &&
         dashType == SkPathEffect::kDash_DashType && info.fCount == 2) {
@@ skipping 26 matching lines @@
   }
 }
 
 AnnotateOp::AnnotateOp(PaintCanvas::AnnotationType annotation_type,
                        const SkRect& rect,
                        sk_sp<SkData> data)
     : annotation_type(annotation_type), rect(rect), data(std::move(data)) {}
 
 AnnotateOp::~AnnotateOp() = default;
 
+DrawDisplayItemListOp::DrawDisplayItemListOp(
+    scoped_refptr<DisplayItemList> list)
+    : list(list) {}
+
+size_t DrawDisplayItemListOp::AdditionalBytesUsed() const {
+  return list->ApproximateMemoryUsage();
+}
+
+DrawDisplayItemListOp::DrawDisplayItemListOp(const DrawDisplayItemListOp& op) =
+    default;
+
+DrawDisplayItemListOp& DrawDisplayItemListOp::operator=(
+    const DrawDisplayItemListOp& op) = default;
+
 DrawDisplayItemListOp::~DrawDisplayItemListOp() = default;
 
 DrawImageOp::DrawImageOp(const PaintImage& image,
                          SkScalar left,
                          SkScalar top,
                          const PaintFlags* flags)
     : image(image),
       left(left),
       top(top),
       flags(flags ? *flags : PaintFlags()) {}
@@ skipping 122 matching lines @@
 }
 
 void PaintOpBuffer::ShrinkToFit() {
   if (!used_ || used_ == reserved_)
     return;
   data_.realloc(used_);
   reserved_ = used_;
 }
 
 }  // namespace cc