Revamp OffscreenCanvas commit flow

content/browser/renderer_host/offscreen_canvas_surface_impl.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/offscreen_canvas_surface_impl.h"
 
 #include <utility>
 
 #include "base/bind_helpers.h"
 #include "cc/surfaces/surface.h"
 #include "cc/surfaces/surface_manager.h"
 #include "content/browser/compositor/surface_utils.h"
 #include "content/browser/renderer_host/offscreen_canvas_surface_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
 
 namespace content {
 
-OffscreenCanvasSurfaceImpl::OffscreenCanvasSurfaceImpl()
-    : id_allocator_(new cc::SurfaceIdAllocator()) {}
+OffscreenCanvasSurfaceImpl::OffscreenCanvasSurfaceImpl() {}
 
 OffscreenCanvasSurfaceImpl::~OffscreenCanvasSurfaceImpl() {
   if (frame_sink_id_.is_valid()) {
     OffscreenCanvasSurfaceManager::GetInstance()
         ->UnregisterOffscreenCanvasSurfaceInstance(frame_sink_id_);
   }
 }
 
 // static
 void OffscreenCanvasSurfaceImpl::Create(
     mojo::InterfaceRequest<blink::mojom::OffscreenCanvasSurface> request) {
   mojo::MakeStrongBinding(base::MakeUnique<OffscreenCanvasSurfaceImpl>(),
                           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,
                                          const cc::SurfaceSequence& sequence) {
   cc::SurfaceManager* manager = GetSurfaceManager();
   cc::Surface* surface = manager->GetSurfaceForId(surface_id);
   if (!surface) {
     DLOG(ERROR) << "Attempting to require callback on nonexistent surface";
     return;
   }
   surface->AddDestructionDependency(sequence);
 }
 
 void OffscreenCanvasSurfaceImpl::Satisfy(const cc::SurfaceSequence& sequence) {
   std::vector<uint32_t> sequences;
   sequences.push_back(sequence.sequence);
   cc::SurfaceManager* manager = GetSurfaceManager();
   manager->DidSatisfySequences(sequence.frame_sink_id, &sequences);
 }
 
 }  // namespace content