Clean up MarkFirstContentfulPaint for canvas.

Follow up to https://chromium-review.googlesource.com/c/chromium/src/+/2348694

Bug: 1114793
Change-Id: I869e238afadd01268456b783da8a848332c3418b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354495Reviewed-by: Philip Rogers <pdr@chromium.org>
Reviewed-by: Nicolás Peña Moreno <npm@chromium.org>
Commit-Queue: Annie Sullivan <sullivan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797864}

third_party/blink/renderer/core/html/canvas/html_canvas_element.cc

@@ -81,7 +81,6 @@
 #include "third_party/blink/renderer/core/page/chrome_client.h"
 #include "third_party/blink/renderer/core/page/page.h"
 #include "third_party/blink/renderer/core/paint/paint_layer.h"
-#include "third_party/blink/renderer/core/paint/paint_timing.h"
 #include "third_party/blink/renderer/core/probe/core_probes.h"
 #include "third_party/blink/renderer/platform/bindings/exception_state.h"
 #include "third_party/blink/renderer/platform/graphics/canvas_resource_dispatcher.h"
@@ -814,9 +813,6 @@ void HTMLCanvasElement::Paint(GraphicsContext& context,
   if (!context_ && !OffscreenCanvasFrame())
     return;
 
-  if (!canvas_is_clear_)
-    PaintTiming::From(GetDocument()).MarkFirstContentfulPaint();
-
   // If the canvas is gpu composited, it has another way of getting to screen
   if (!PaintsIntoCanvasBuffer()) {
     // For click-and-drag or printing we still want to draw

third_party/blink/renderer/core/html/canvas/html_canvas_element.h

@@ -310,6 +310,8 @@ class CORE_EXPORT HTMLCanvasElement final
   // returned.
   RespectImageOrientationEnum RespectImageOrientation() const;
 
+  bool IsCanvasClear() { return canvas_is_clear_; }
+
  protected:
   void DidMoveToNewDocument(Document& old_document) override;
 

third_party/blink/renderer/core/paint/html_canvas_painter.cc

@@ -39,14 +39,16 @@ void HTMLCanvasPainter::PaintReplaced(const PaintInfo& paint_info,
   paint_rect.Move(paint_offset);
 
   auto* canvas = To<HTMLCanvasElement>(layout_html_canvas_.GetNode());
+  if (!canvas->IsCanvasClear()) {
+    PaintTiming::From(layout_html_canvas_.GetDocument())
+        .MarkFirstContentfulPaint();
+  }
 
   bool flatten_composited_layers =
       paint_info.GetGlobalPaintFlags() & kGlobalPaintFlattenCompositingLayers;
   if (RuntimeEnabledFeatures::CompositeAfterPaintEnabled() &&
       !flatten_composited_layers) {
     if (auto* layer = canvas->ContentsCcLayer()) {
-      PaintTiming::From(layout_html_canvas_.GetDocument())
-          .MarkFirstContentfulPaint();
       IntRect pixel_snapped_rect = PixelSnappedIntRect(paint_rect);
       layer->SetBounds(gfx::Size(pixel_snapped_rect.Size()));
       layer->SetIsDrawable(true);