Add stable id to PaintImage.

third_party/WebKit/Source/platform/graphics/Image.cpp

Index: third_party/WebKit/Source/platform/graphics/Image.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/Image.cpp b/third_party/WebKit/Source/platform/graphics/Image.cpp
index 8af49d6721cc861d07342dd7c231efe26879dcb1..be2a1d1525ceb304ff6628014244171ae1a12fbe 100644
--- a/third_party/WebKit/Source/platform/graphics/Image.cpp
+++ b/third_party/WebKit/Source/platform/graphics/Image.cpp
@@ -52,7 +52,9 @@
 namespace blink {
 
 Image::Image(ImageObserver* observer)
-    : image_observer_disabled_(false), image_observer_(observer) {}
+    : image_observer_disabled_(false),
+      image_observer_(observer),
+      stable_image_id_(PaintImage::GetNextId()) {}

[chrishtr, 2017/05/10 22:56:11]

How about making Image the class which creates its own id,
instead of delegating to PaintImage?

[vmpstr, 2017/05/10 23:21:47]

Hm.. You mean have the id generation happen from Image? This id needs to be
unique for any paint image created (unless of course it explicitly references
the same logical image). I'm not sure how to guarantee that without actually
asking PaintImage to get the next id... This is kind of like an Image that
creates its own id, except it just uses PaintImage as the generator.

Do you have a specific concern about this breaking something?

 
 Image::~Image() {}
 
@@ -297,7 +299,8 @@ void Image::DrawPattern(GraphicsContext& context,
   auto image_id = image.sk_image()->uniqueID();
 
   image =
-      PaintImage(image.sk_image()->makeSubset(EnclosingIntRect(norm_src_rect)),
+      PaintImage(stable_image_id_,
+                 image.sk_image()->makeSubset(EnclosingIntRect(norm_src_rect)),
                  image.animation_type(), image.completion_state());
   if (!image)
     return;
@@ -345,7 +348,8 @@ PaintImage Image::PaintImageForCurrentFrame() {
   auto completion_state = CurrentFrameIsComplete()
                               ? PaintImage::CompletionState::DONE
                               : PaintImage::CompletionState::PARTIALLY_DONE;
-  return PaintImage(ImageForCurrentFrame(), animation_type, completion_state);
+  return PaintImage(stable_image_id_, ImageForCurrentFrame(), animation_type,
+                    completion_state);
 }
 
 bool Image::ApplyShader(PaintFlags& flags, const SkMatrix& local_matrix) {