Delegate root layer scroll offset to android_webview.

content/browser/android/in_process/synchronous_compositor_impl.cc

Index: content/browser/android/in_process/synchronous_compositor_impl.cc
diff --git a/content/browser/android/in_process/synchronous_compositor_impl.cc b/content/browser/android/in_process/synchronous_compositor_impl.cc
index 425788b99bffc26cf810eb18f40be38a4a1d1367..594906b951a0cdf7e19cd73e41d4f39f7d7c77bf 100644
--- a/content/browser/android/in_process/synchronous_compositor_impl.cc
+++ b/content/browser/android/in_process/synchronous_compositor_impl.cc
@@ -6,6 +6,8 @@
 
 #include "base/lazy_instance.h"
 #include "base/message_loop.h"
+#include "cc/input/input_handler.h"
+#include "cc/input/layer_scroll_offset_delegate.h"
 #include "content/browser/android/in_process/synchronous_input_event_filter.h"
 #include "content/public/browser/android/synchronous_compositor_client.h"
 #include "content/public/browser/browser_thread.h"
@@ -111,7 +113,8 @@ SynchronousCompositorImpl* SynchronousCompositorImpl::FromRoutingID(
 SynchronousCompositorImpl::SynchronousCompositorImpl(WebContents* contents)
     : compositor_client_(NULL),
       output_surface_(NULL),
-      contents_(contents) {
+      contents_(contents),
+      input_handler_(NULL) {
   DCHECK(contents);
 }
 
@@ -149,6 +152,11 @@ bool SynchronousCompositorImpl::DemandDrawSw(SkCanvas* canvas) {
   return output_surface_->DemandDrawSw(canvas);
 }
 
+void SynchronousCompositorImpl::DidChangeRootLayerScrollOffset() {
+  if (input_handler_)
+    input_handler_->OnRootLayerDelegatedScrollOffsetChanged();
+}
+
 void SynchronousCompositorImpl::DidBindOutputSurface(
       SynchronousCompositorOutputSurface* output_surface) {
   DCHECK(CalledOnValidThread());
@@ -160,6 +168,7 @@ void SynchronousCompositorImpl::DidBindOutputSurface(
 void SynchronousCompositorImpl::DidDestroySynchronousOutputSurface(
        SynchronousCompositorOutputSurface* output_surface) {
   DCHECK(CalledOnValidThread());
+
   // Allow for transient hand-over when two output surfaces may refer to
   // a single delegate.
   if (output_surface_ == output_surface) {
@@ -170,6 +179,19 @@ void SynchronousCompositorImpl::DidDestroySynchronousOutputSurface(
   }
 }
 
+void SynchronousCompositorImpl::SetInputHandler(
+    cc::InputHandler* input_handler) {
+  DCHECK(CalledOnValidThread());
+
+  if (input_handler_)
+    input_handler_->SetRootLayerScrollOffsetDelegate(NULL);
+
+  input_handler_ = input_handler;
+
+  if (input_handler_)
+    input_handler_->SetRootLayerScrollOffsetDelegate(this);
+}
+
 void SynchronousCompositorImpl::SetContinuousInvalidate(bool enable) {
   DCHECK(CalledOnValidThread());
   if (compositor_client_)
@@ -183,6 +205,19 @@ InputEventAckState SynchronousCompositorImpl::HandleInputEvent(
       contents_->GetRoutingID(), input_event);
 }
 
+void SynchronousCompositorImpl::SetTotalScrollOffset(gfx::Vector2dF new_value) {
+  DCHECK(CalledOnValidThread());
+  if (compositor_client_)
+    compositor_client_->SetTotalRootLayerScrollOffset(new_value);
+}
+
+gfx::Vector2dF SynchronousCompositorImpl::GetTotalScrollOffset() {
+  DCHECK(CalledOnValidThread());
+  if (compositor_client_)
+    return compositor_client_->GetTotalRootLayerScrollOffset();
+  return gfx::Vector2dF();
+}
+
 // Not using base::NonThreadSafe as we want to enforce a more exacting threading
 // requirement: SynchronousCompositorImpl() must only be used on the UI thread.
 bool SynchronousCompositorImpl::CalledOnValidThread() const {