Remove Useless Variable |usage_counters_| in canvas

Change-Id: Ic2846811bcaadd612ed40475adae95f469044ff6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2050577
Commit-Queue: Yi Xu <yiyix@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742914}

third_party/blink/renderer/modules/canvas/canvas2d/base_rendering_context_2d.cc

@@ -855,8 +855,6 @@ void BaseRenderingContext2D::clearRect(double x,
                                        double y,
                                        double width,
                                        double height) {
-  usage_counters_.num_clear_rect_calls++;
-
   if (!ValidateRectForCanvas(x, y, width, height))
     return;
 
@@ -1559,8 +1557,6 @@ ImageData* BaseRenderingContext2D::getImageData(
 
   base::TimeTicks start_time = base::TimeTicks::Now();
 
-  usage_counters_.num_get_image_data_calls++;
-  usage_counters_.area_get_image_data_calls += sw * sh;
   if (!OriginClean()) {
     exception_state.ThrowSecurityError(
         "The canvas has been tainted by cross-origin data.");
@@ -1722,8 +1718,6 @@ void BaseRenderingContext2D::putImageData(ImageData* data,
     return;
   }
   base::TimeTicks start_time = base::TimeTicks::Now();
-  usage_counters_.num_put_image_data_calls++;
-  usage_counters_.area_put_image_data_calls += dirty_width * dirty_height;
 
   if (data->BufferBase()->IsDetached()) {
     exception_state.ThrowDOMException(DOMExceptionCode::kInvalidStateError,
@@ -1998,11 +1992,6 @@ void BaseRenderingContext2D::setTextBaseline(const String& s) {
   ModifiableState().SetTextBaseline(baseline);
 }
 
-const BaseRenderingContext2D::UsageCounters&
-BaseRenderingContext2D::GetUsage() {
-  return usage_counters_;
-}
-
 void BaseRenderingContext2D::Trace(Visitor* visitor) {
   visitor->Trace(state_stack_);
 }

third_party/blink/renderer/modules/canvas/canvas2d/base_rendering_context_2d.h

@@ -366,8 +366,6 @@ class MODULES_EXPORT BaseRenderingContext2D : public GarbageCollectedMixin,
   HeapVector<Member<CanvasRenderingContext2DState>> state_stack_;
   AntiAliasingMode clip_antialiasing_;
 
-  mutable UsageCounters usage_counters_;
-
   virtual void FinalizeFrame() {}
 
   float GetFontBaseline(const SimpleFontData&) const;

third_party/blink/renderer/modules/canvas/canvas2d/canvas_rendering_context_2d.cc

@@ -678,7 +678,6 @@ void CanvasRenderingContext2D::FinalizeFrame() {
   TRACE_EVENT0("blink", "CanvasRenderingContext2D::FinalizeFrame");
   if (IsPaintable())
     canvas()->GetCanvas2DLayerBridge()->FinalizeFrame();
-  usage_counters_.num_frames_since_reset++;
 }
 
 bool CanvasRenderingContext2D::ParseColorOrCurrentColor(
@@ -1012,7 +1011,6 @@ bool CanvasRenderingContext2D::FocusRingCallIsValid(const Path& path,
 }
 
 void CanvasRenderingContext2D::DrawFocusRing(const Path& path) {
-  usage_counters_.num_draw_focus_calls++;
   if (!GetOrCreatePaintCanvas())
     return;