Delegate root layer scroll offset to android_webview.

content/renderer/android/synchronous_compositor_impl.cc

+// Copyright 2013 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/renderer/android/synchronous_compositor_impl.h"
+
+#include "base/message_loop.h"
+#include "cc/input/input_handler.h"
+#include "content/public/renderer/android/synchronous_compositor_client.h"
+#include "content/public/renderer/content_renderer_client.h"
+
+namespace content {
+
+SynchronousCompositorImpl::SynchronousCompositorImpl(int32 routing_id)
+    : routing_id_(routing_id), compositor_client_(NULL) {}
+
+SynchronousCompositorImpl::~SynchronousCompositorImpl() {
+}
+
+scoped_ptr<cc::OutputSurface>
+SynchronousCompositorImpl::CreateOutputSurface() {
+  scoped_ptr<SynchronousCompositorOutputSurface> output_surface(
+      new SynchronousCompositorOutputSurface(this));
+  output_surface_ = output_surface.get();
+  return output_surface.PassAs<cc::OutputSurface>();
+}
+
+void SynchronousCompositorImpl::didCreateInputHandler(
+    base::WeakPtr<cc::InputHandler> input_handler) {
+  // TODO(mkosiba): Seems contrived (also, current version has race,
+  // would need to ref-count SynchronousCompositorImpl).
+  // Need to find a better way for the SynchronousCompositorImpl to 'get' an
+  // input handler and to be notified of when the InputHandler is destroyed.
+  GetContentClient()->renderer()->OverrideCompositorMessageLoop()->PostTask(

[jamesr, 2013/05/22 01:28:13]

this looks needlessly indirect.  you're in the content implementation here, you
can get to the compositor thread, and you know this view's routing_id.
content::InputHandlerManager maintains a map of routing_ids to InputHandler
instances.  This class should coordinate with the InputHandlerManager to do
whatever work needs doing

[mkosiba (inactive), 2013/05/22 17:26:17]

Done.

+      FROM_HERE,
+      base::Bind(&SynchronousCompositorImpl::didCreateInputHandlerOnImplThread,
+                 base::Unretained(this)
+                 input_handler));
+}
+
+void SynchronousCompositorImpl::didCreateInputHandlerOnImplThread(
+      base::WeakPtr<cc::InputHandler> input_handler) {
+  if (input_handler.get()) {
+    input_handler->SetRootLayerScrollOffsetDelegate(
+        GetSynchronousCompositor());
+  }
+}
+
+bool SynchronousCompositorImpl::IsHwReady() {
+  DCHECK(CalledOnValidThread());
+  DCHECK(output_surface_);
+
+  if (!output_surface_)
+    return false;
+  return output_surface_->IsHwReady();
+}
+
+void SynchronousCompositorImpl::SetClient(
+    SynchronousCompositorClient* compositor_client) {
+  DCHECK(CalledOnValidThread());
+  compositor_client_ = compositor_client;
+}
+
+bool SynchronousCompositorImpl::DemandDrawSw(SkCanvas* canvas) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(output_surface_);
+
+  if (!output_surface_)
+    return false;
+
+  return output_surface_->DemandDrawSw(canvas);
+}
+
+bool SynchronousCompositorImpl::DemandDrawHw(
+      gfx::Size view_size,
+      const gfx::Transform& transform,
+      gfx::Rect damage_area) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(output_surface_);
+
+  if (!output_surface_)
+    return false;
+  return output_surface_->DemandDrawHw(view_size, transform, damage_area);
+}
+
+void SynchronousCompositorImpl::SetContinuousInvalidate(bool enable) {
+  DCHECK(CalledOnValidThread());
+  compositor_client_->SetContinuousInvalidate(enable);
+}
+
+void SynchronousCompositorImpl::DidCreateSynchronousCompositor() {
+  DCHECK(CalledOnValidThread());
+  GetContentClient()->renderer()->DidCreateSynchronousCompositor(routing_id_,
+                                                                 this);
+}
+
+void SynchronousCompositorImpl::DidDestroyCompositor() {
+  DCHECK(CalledOnValidThread());
+  output_surface_ = NULL;
+}
+
+void SynchronousCompositorImpl::SetTotalScrollOffset(gfx::Vector2dF new_value) {
+  DCHECK(CalledOnValidThread());
+  compositor_client_->SetTotalRootLayerScrollOffset(new_value);
+}
+
+gfx::Vector2dF SynchronousCompositorImpl::GetTotalScrollOffset() {
+  DCHECK(CalledOnValidThread());
+  return compositor_client_->GetTotalRootLayerScrollOffset();
+}
+
+// Not using base::NonThreadSafe as we want to enforce a more exacting threading
+// requirement: SynchronousCompositorImpl() must only be used by
+// embedders that supply their own compositor loop via
+// OverrideCompositorMessageLoop().
+bool SynchronousCompositorImpl::CalledOnValidThread() const {
+  return base::MessageLoop::current() && (base::MessageLoop::current() ==
+      GetContentClient()->renderer()->OverrideCompositorMessageLoop());
+}
+
+}  // namespace content