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 4b70c9b455256ea72c1591beb3dc358d60782cc5..3decfef28ae77f9c0c62edcf997646123f2a483a 100644
--- a/content/browser/android/in_process/synchronous_compositor_impl.cc
+++ b/content/browser/android/in_process/synchronous_compositor_impl.cc
@@ -6,11 +6,14 @@
 
 #include "base/lazy_instance.h"
 #include "base/message_loop.h"
+#include "cc/input/layer_scroll_offset_delegate.h"
 #include "content/public/browser/android/synchronous_compositor_client.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/renderer/android/synchronous_compositor_factory.h"
+#include "content/renderer/gpu/input_handler_manager.h"
+#include "content/renderer/render_thread_impl.h"
 
 namespace content {
 
@@ -31,7 +34,7 @@ int GetInProcessRendererId() {
   return id;
 }
 
-class SynchronousCompositorFactoryImpl : public SynchronousCompositorFactory {
+class SynchronousCompositorFactoryImpl: public SynchronousCompositorFactory {

[joth, 2013/06/01 02:11:35]

undo edit

[mkosiba (inactive), 2013/06/06 17:55:10]

why? was the space in front of the colon intentional? 

[joth, 2013/06/06 20:19:32]

Of course! We always have a space either side of that colon.

$ git grep " : public" | wc -l
15034
$ git grep "\w: public" | wc -l
106

  public:
   SynchronousCompositorFactoryImpl() {
     SynchronousCompositorFactory::SetInstance(this);
@@ -75,6 +78,10 @@ SynchronousCompositorImpl::SynchronousCompositorImpl(WebContents* contents)
     : compositor_client_(NULL),
       output_surface_(NULL),
       contents_(contents) {
+  DCHECK(RenderThread::Get()->GetMessageLoop() == base::MessageLoop::current());

[joth, 2013/06/01 02:11:35]

I can't work out why this would be. There's only one call to create this class,
SynchronousCompositorImpl::CreateForWebContents below, and it can only happen on
UI thread (it takes a WebContents* which would be very hard to ever get hold of
on render main thread)

[mkosiba (inactive), 2013/06/06 17:55:10]

I think you misunderstood me about which main thread I was asking when I asked
you over IM whether this class is created on the main thread. I was thinking of
the main renderer thread, you were thinking of the main UI thread :)

[joth, 2013/06/06 20:19:32]

Opps! sorry for confusion.
(I've learnt the new meaning of 'main' thread in verbal conversation, but
obviously I still get tripped up in IM chatting..)

+
+  input_handler_manager_ = RenderThreadImpl::current()->input_handler_manager();
+  // TODO(mkosiba): DCHECK(input_handler_manager_); after Jared's patches land.
 }
 
 SynchronousCompositorImpl::~SynchronousCompositorImpl() {
@@ -118,11 +125,18 @@ void SynchronousCompositorImpl::DidBindOutputSurface(
   output_surface_ = output_surface;
   if (compositor_client_)
     compositor_client_->DidInitializeCompositor(this);
+
+  if (input_handler_manager_)
+    input_handler_manager_->SetRootLayerScrollDelegate(routing_id_, this);
 }
 
 void SynchronousCompositorImpl::DidDestroySynchronousOutputSurface(
        SynchronousCompositorOutputSurface* output_surface) {
   DCHECK(CalledOnValidThread());
+
+  if (input_handler_manager_)
+    input_handler_manager_->SetRootLayerScrollDelegate(routing_id_, NULL);
+
   // Allow for transient hand-over when two output surfaces may refer to
   // a single delegate.
   if (output_surface_ == output_surface) {
@@ -139,6 +153,20 @@ void SynchronousCompositorImpl::SetContinuousInvalidate(bool enable) {
     compositor_client_->SetContinuousInvalidate(enable);
 }
 
+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();
+  else
+    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 {