Revamp OffscreenCanvas commit flow

content/browser/renderer_host/offscreen_canvas_surface_impl.cc

Index: content/browser/renderer_host/offscreen_canvas_surface_impl.cc
diff --git a/content/browser/renderer_host/offscreen_canvas_surface_impl.cc b/content/browser/renderer_host/offscreen_canvas_surface_impl.cc
index 29679540fa365f8c20961cffd571b7762c55ddf2..b17cae5e5f98ebda68b36f25d181a2c72468e621 100644
--- a/content/browser/renderer_host/offscreen_canvas_surface_impl.cc
+++ b/content/browser/renderer_host/offscreen_canvas_surface_impl.cc
@@ -16,8 +16,7 @@
 
 namespace content {
 
-OffscreenCanvasSurfaceImpl::OffscreenCanvasSurfaceImpl()
-    : id_allocator_(new cc::SurfaceIdAllocator()) {}
+OffscreenCanvasSurfaceImpl::OffscreenCanvasSurfaceImpl() {}
 
 OffscreenCanvasSurfaceImpl::~OffscreenCanvasSurfaceImpl() {
   if (frame_sink_id_.is_valid()) {
@@ -33,29 +32,40 @@ void OffscreenCanvasSurfaceImpl::Create(
                           std::move(request));
 }
 
-void OffscreenCanvasSurfaceImpl::GetSurfaceId(GetSurfaceIdCallback callback) {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+void OffscreenCanvasSurfaceImpl::SetClient(
+    blink::mojom::OffscreenCanvasSurfaceClientPtr client,
+    const cc::FrameSinkId& frame_sink_id) {
   if (frame_sink_id_.is_valid()) {
     // This IPC should be only called once for each HTMLCanvasElement. In this
     // case, frame_sink_id_ is still unset.
     // As the browser makes no assumption of correct behavior of renderer, in
-    // an unwanted situation when this function is invoked twice, we need to
-    // unregister the instance from manager.
-    OffscreenCanvasSurfaceManager::GetInstance()
-        ->UnregisterOffscreenCanvasSurfaceInstance(frame_sink_id_);
+    // an unwanted situation when this function is invoked twice, we ignore
+    // the second call.
     mojo::ReportBadMessage(
-        "The same OffscreenCanvasSurfaceImpl is registered to "
-        "OffscreenCanvasSurfaceManager twice.");
+        "The same OffscreenCanvasSurfaceImpl sets client "
+        "twice.");
+    return;
   }
-
-  frame_sink_id_ = AllocateFrameSinkId();
-  cc::SurfaceId surface_id =
-      cc::SurfaceId(frame_sink_id_, id_allocator_->GenerateId());
+  client_ = std::move(client);
+  frame_sink_id_ = frame_sink_id;
 
   OffscreenCanvasSurfaceManager::GetInstance()
       ->RegisterOffscreenCanvasSurfaceInstance(frame_sink_id_, this);
+}
 
-  std::move(callback).Run(surface_id);
+void OffscreenCanvasSurfaceImpl::OnSurfaceCreated(
+    const cc::SurfaceId& surface_id,
+    const gfx::Size& frame_size,
+    float device_scale_factor) {
+  DCHECK_EQ(surface_id.frame_sink_id(), frame_sink_id_);
+  if (!current_local_frame_id_.is_valid() ||
+      surface_id.local_frame_id() != current_local_frame_id_) {
+    current_local_frame_id_ = surface_id.local_frame_id();
+    if (client_) {
+      client_->OnSurfaceCreated(surface_id, frame_size.width(),
+                                frame_size.height(), device_scale_factor);
+    }
+  }
 }
 
 void OffscreenCanvasSurfaceImpl::Require(const cc::SurfaceId& surface_id,