[Paint Preview] Account for scroll offset in subframes

Scroll position isn't accounted for in the clip rect for subframes. It
needs to be manually corrected via the tracker when serializing.

Bug: 1090920
Change-Id: I93e316016832132cbfdfec833249ed454c060b9c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2228577Reviewed-by: Mehran Mahmoudi <mahmoudi@chromium.org>
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#775098}

components/paint_preview/common/paint_preview_tracker.cc

@@ -51,7 +51,8 @@ uint32_t PaintPreviewTracker::CreateContentForRemoteFrame(
     const gfx::Rect& rect,
     const base::UnguessableToken& embedding_token) {
   sk_sp<SkPicture> pic = SkPicture::MakePlaceholder(
-      SkRect::MakeXYWH(rect.x(), rect.y(), rect.width(), rect.height()));
+      SkRect::MakeXYWH(rect.x() + scroll_.width(), rect.y() + scroll_.height(),
+                       rect.width(), rect.height()));
   const uint32_t content_id = pic->uniqueID();
   DCHECK(!base::Contains(content_id_to_embedding_token_, content_id));
   content_id_to_embedding_token_[content_id] = embedding_token;
@@ -59,6 +60,10 @@ uint32_t PaintPreviewTracker::CreateContentForRemoteFrame(
   return content_id;
 }
 
+void PaintPreviewTracker::SetScrollForFrame(const SkISize& scroll) {
+  scroll_ = scroll;
+}
+
 void PaintPreviewTracker::AddGlyphs(const SkTextBlob* blob) {
   if (!blob)
     return;

components/paint_preview/common/paint_preview_tracker.h

@@ -50,6 +50,9 @@ class PaintPreviewTracker {
       const gfx::Rect& rect,
       const base::UnguessableToken& embedding_token);
 
+  // Sets the scroll position for the top layer frame.
+  void SetScrollForFrame(const SkISize& scroll);
+
   // Adds the glyphs in |blob| to the glyph usage tracker for the |blob|'s
   // associated typface.
   void AddGlyphs(const SkTextBlob* blob);
@@ -83,6 +86,8 @@ class PaintPreviewTracker {
   const base::Optional<base::UnguessableToken> embedding_token_;
   const bool is_main_frame_;
 
+  SkISize scroll_;
+
   std::vector<mojom::LinkDataPtr> links_;
   PictureSerializationContext content_id_to_embedding_token_;
   TypefaceUsageMap typeface_glyph_usage_;

components/paint_preview/common/paint_preview_tracker_unittest.cc

@@ -61,6 +61,33 @@ TEST(PaintPreviewTrackerTest, TestRemoteFramePlaceholderPicture) {
   // underlying private picture record.
 }
 
+TEST(PaintPreviewTrackerTest, TestRemoteFramePlaceholderPictureWithScroll) {
+  const base::UnguessableToken kDocToken = base::UnguessableToken::Create();
+  const base::UnguessableToken kEmbeddingToken =
+      base::UnguessableToken::Create();
+  PaintPreviewTracker tracker(kDocToken, kEmbeddingToken, true);
+  tracker.SetScrollForFrame(SkISize::Make(10, 20));
+
+  const base::UnguessableToken kEmbeddingTokenChild =
+      base::UnguessableToken::Create();
+  gfx::Rect rect(50, 40, 30, 20);
+  uint32_t content_id =
+      tracker.CreateContentForRemoteFrame(rect, kEmbeddingTokenChild);
+  PictureSerializationContext* context =
+      tracker.GetPictureSerializationContext();
+  EXPECT_TRUE(context->count(content_id));
+  EXPECT_EQ((*context)[content_id], kEmbeddingTokenChild);
+
+  SkPictureRecorder recorder;
+  SkCanvas* canvas = recorder.beginRecording(100, 100);
+  tracker.CustomDataToSkPictureCallback(canvas, content_id);
+  sk_sp<SkPicture> pic = recorder.finishRecordingAsPicture();
+
+  // TODO(crbug/1009552): find a good way to check that a filler picture was
+  // actually inserted into |pic|. This is difficult without using the
+  // underlying private picture record.
+}
+
 TEST(PaintPreviewTrackerTest, TestGlyphRunList) {
   const base::UnguessableToken kEmbeddingToken =
       base::UnguessableToken::Create();

components/paint_preview/renderer/paint_preview_recorder_impl.cc

@@ -155,9 +155,12 @@ void PaintPreviewRecorderImpl::CapturePaintPreviewInternal(
     bounds = gfx::Rect(params->clip_rect.size());
   }
 
-  cc::PaintRecorder recorder;
   auto tracker = std::make_unique<PaintPreviewTracker>(
       params->guid, frame->GetEmbeddingToken(), is_main_frame_);
+  auto size = frame->GetScrollOffset();
+  tracker->SetScrollForFrame(SkISize::Make(size.width, size.height));
+
+  cc::PaintRecorder recorder;
   cc::PaintCanvas* canvas =
       recorder.beginRecording(bounds.width(), bounds.height());
   canvas->SetPaintPreviewTracker(tracker.get());