Making Clear private and removing a last not-needed clear

Clear was not yet private as it was still being used by Canvas 2D
Layer Bridge.

Removing that usage now, and marking Clear as Private inside Canvas
Resource Provider.

Adding an explicit DidDraw to the creation of the Resource, as it has
been cleared on construction.

I am leaving a GetOrCreateResourceProvider in line 101 as it was called,
and that would, potentially, recreate the Resource.
It would be also a good follow-up to try to see if there is a way to
encapsulate the things DidDraw is doing here and in other places where
it is being called after the internal Clear of the CRP, to have it done
internally as well.

Bug: 1090081
Change-Id: I87a5b6d20a1d79606e1d986c484f2677edde2863
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2382612Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Commit-Queue: Juanmi Huertas <juanmihd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804237}

third_party/blink/renderer/platform/graphics/canvas_2d_layer_bridge.cc

@@ -97,10 +97,6 @@ Canvas2DLayerBridge::~Canvas2DLayerBridge() {
 
 void Canvas2DLayerBridge::SetCanvasResourceHost(CanvasResourceHost* host) {
   resource_host_ = host;
-
-  if (resource_host_ && GetOrCreateResourceProvider()) {
-    EnsureCleared();
-  }
 }
 
 void Canvas2DLayerBridge::ResetResourceProvider() {
@@ -259,7 +255,10 @@ CanvasResourceProvider* Canvas2DLayerBridge::GetOrCreateResourceProvider() {
   if (!resource_provider || !resource_provider->IsValid())
     return nullptr;
 
-  EnsureCleared();
+  // Calling to DidDraw because GetOrCreateResourceProvider created a new
+  // provider and cleared it
+  // TODO crbug/1090081: Check possibility to move DidDraw inside Clear.
+  DidDraw(FloatRect(0.f, 0.f, size_.Width(), size_.Height()));
 
   if (IsAccelerated() && !layer_) {
     layer_ = cc::TextureLayer::CreateForMailbox(this);
@@ -394,14 +393,6 @@ void Canvas2DLayerBridge::SkipQueuedDrawCommands() {
     rate_limiter_->Reset();
 }
 
-void Canvas2DLayerBridge::EnsureCleared() {
-  if (cleared_)
-    return;
-  cleared_ = true;
-  ResourceProvider()->Clear();
-  DidDraw(FloatRect(0.f, 0.f, size_.Width(), size_.Height()));
-}
-
 void Canvas2DLayerBridge::ClearPendingRasterTimers() {
   gpu::raster::RasterInterface* raster_interface = nullptr;
   if (IsAccelerated() && SharedGpuContext::ContextProviderWrapper() &&

third_party/blink/renderer/platform/graphics/canvas_2d_layer_bridge.h

@@ -177,7 +177,6 @@ class PLATFORM_EXPORT Canvas2DLayerBridge : public cc::TextureLayerClient {
   void ResetResourceProvider();
 
   void SkipQueuedDrawCommands();
-  void EnsureCleared();
 
   // Check if the Raster Mode is GPU and if the GPU context is not lost
   bool ShouldAccelerate() const;
@@ -232,10 +231,6 @@ class PLATFORM_EXPORT Canvas2DLayerBridge : public cc::TextureLayerClient {
 
   sk_sp<cc::PaintRecord> last_recording_;
 
-  // This tracks whether the canvas has been cleared once after
-  // this bridge was created.
-  bool cleared_ = false;
-
   base::WeakPtrFactory<Canvas2DLayerBridge> weak_ptr_factory_{this};
 
   DISALLOW_COPY_AND_ASSIGN(Canvas2DLayerBridge);

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

@@ -198,7 +198,7 @@ class PLATFORM_EXPORT CanvasResourceProvider
     NOTREACHED();
     return nullptr;
   }
-  void Clear();
+
   ~CanvasResourceProvider() override;
 
   base::WeakPtr<CanvasResourceProvider> CreateWeakPtr() {
@@ -292,6 +292,8 @@ class PLATFORM_EXPORT CanvasResourceProvider
   void EnsureSkiaCanvas();
   void SetNeedsFlush() { needs_flush_ = true; }
 
+  void Clear();
+
   base::WeakPtr<WebGraphicsContext3DProviderWrapper> context_provider_wrapper_;
   base::WeakPtr<CanvasResourceDispatcher> resource_dispatcher_;
   const IntSize size_;