canvas2d: Fix canvas resource thrashing with an intermediate canvas.

If a canvas is used as an intermediate for drawing to the displayed
canvas multiple times in a frame, then a ref to its backing texture is
retained in the displayed canvas' paint recording. This triggers a
copy-on-write and a buffer allocation each time this intermediate canvas
is updated for a new draw.

The above allocation can be avoided by ordering the GPU work
to write to and read from the intermediate canvas' buffer correctly and
reuse the buffer for each update to this intermediate canvas.
CanvasResourceProviderSharedImage did this optimization earlier by
flushing skia prior to triggering a copy-on-write. But after disabling
deferral for texture backed images, the draw for that texture is never
flushed to skia until the displayed canvas' paint recording is flushed.

This change brings back the optimization by flushing a canvas' recording
each time a texture backed image is drawn to it.

R=fserb@chromium.org, bsalomon@google.com

Bug: 1030108
Change-Id: Id46fa8399f64a4c724c9f51e5cb4927b7e97d747
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2040028Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Reviewed-by: Aaron Krajeski <aaronhk@chromium.org>
Commit-Queue: Fernando Serboncini <fserb@chromium.org>
Auto-Submit: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#740005}

third_party/blink/renderer/platform/graphics/memory_managed_paint_canvas.cc

@@ -21,7 +21,7 @@ void MemoryManagedPaintCanvas::drawImage(const cc::PaintImage& image,
                                          const cc::PaintFlags* flags) {
   DCHECK(!image.IsPaintWorklet());
   RecordPaintCanvas::drawImage(image, left, top, flags);
-  UpdateMemoryUsage(image);
+  RequestFlushAfterDrawIfNeeded(image);
 }
 
 void MemoryManagedPaintCanvas::drawImageRect(
@@ -31,10 +31,16 @@ void MemoryManagedPaintCanvas::drawImageRect(
     const cc::PaintFlags* flags,
     PaintCanvas::SrcRectConstraint constraint) {
   RecordPaintCanvas::drawImageRect(image, src, dst, flags, constraint);
-  UpdateMemoryUsage(image);
+  RequestFlushAfterDrawIfNeeded(image);
 }
 
-void MemoryManagedPaintCanvas::UpdateMemoryUsage(const cc::PaintImage& image) {
+void MemoryManagedPaintCanvas::RequestFlushAfterDrawIfNeeded(
+    const cc::PaintImage& image) {
+  if (image.IsTextureBacked()) {
+    set_needs_flush_callback_.Run();
+    return;
+  }
+
   if (cached_image_ids_.contains(image.content_id()))
     return;
 

third_party/blink/renderer/platform/graphics/memory_managed_paint_canvas.h

@@ -36,7 +36,7 @@ class PLATFORM_EXPORT MemoryManagedPaintCanvas final
                      SrcRectConstraint constraint) override;
 
  private:
-  void UpdateMemoryUsage(const cc::PaintImage& image);
+  void RequestFlushAfterDrawIfNeeded(const cc::PaintImage& image);
 
   base::flat_set<int> cached_image_ids_;
   uint64_t total_stored_image_memory_ = 0;