cc: Keep PaintImage in DrawImage.

cc/paint/discardable_image_store.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/discardable_image_store.h"
 
 #include "base/containers/adapters.h"
 #include "base/memory/ptr_util.h"
 #include "cc/paint/display_item_list.h"
 #include "third_party/skia/include/utils/SkNoDrawCanvas.h"
@@ skipping 169 matching lines @@
   if (shader) {
     SkMatrix matrix;
     SkShader::TileMode xy[2];
     SkImage* image = shader->isAImage(&matrix, xy);
     if (image) {
       PaintImage paint_image(sk_ref_sp(image),
                              PaintImage::AnimationType::UNKNOWN,
                              PaintImage::CompletionState::UNKNOWN);
       // TODO(ericrk): Handle cases where we only need a sub-rect from the
       // image. crbug.com/671821
-      AddImage(paint_image, SkRect::MakeFromIRect(image->bounds()), rect,
-               &matrix, flags);
+      AddImage(std::move(paint_image), SkRect::MakeFromIRect(image->bounds()),
+               rect, &matrix, flags);
     }
   }
 }
 
-void DiscardableImageStore::AddImage(const PaintImage& paint_image,
+void DiscardableImageStore::AddImage(PaintImage paint_image,
                                      const SkRect& src_rect,
                                      const SkRect& rect,
                                      const SkMatrix* local_matrix,
                                      const PaintFlags& flags) {
-  sk_sp<const SkImage> sk_image = paint_image.sk_image();
-  if (!sk_image->isLazyGenerated())
+  if (!paint_image.sk_image()->isLazyGenerated())
     return;
 
   const SkRect& clip_rect = SkRect::Make(canvas_->getDeviceClipBounds());
   const SkMatrix& ctm = canvas_->getTotalMatrix();
 
   SkRect paint_rect = MapRect(ctm, rect);
   bool computed_paint_bounds =
       canvas_->ComputePaintBounds(paint_rect, ToSkPaint(&flags), &paint_rect);
   if (!computed_paint_bounds) {
     // TODO(vmpstr): UMA this case.
@@ skipping 23 matching lines @@
   image_rect.Inset(-1, -1);
 
   // The true target color space will be assigned when it is known, in
   // GetDiscardableImagesInRect.
   gfx::ColorSpace target_color_space;
 
   SkMatrix matrix = ctm;
   if (local_matrix)
     matrix.postConcat(*local_matrix);
 
-  // TODO(khushalsagar): Keep PaintImage in DrawImage.
-  (*image_id_to_rect_)[sk_image->uniqueID()].Union(image_rect);
+  (*image_id_to_rect_)[paint_image.sk_image()->uniqueID()].Union(image_rect);

[vmpstr, 2017/05/09 22:42:54]

can you make a comment here to explain why we use the sk image id instead of the
stable id

   image_set_->push_back(
-      std::make_pair(DrawImage(std::move(sk_image), src_irect, filter_quality,
-                               matrix, target_color_space),
+      std::make_pair(DrawImage(std::move(paint_image), src_irect,
+                               filter_quality, matrix, target_color_space),
                      image_rect));
 }
 
 }  // namespace cc