Refactor compositor event handling path to be callback-based

content/renderer/input/input_handler_manager_client.h

Index: content/renderer/input/input_handler_manager_client.h
diff --git a/content/renderer/input/input_handler_manager_client.h b/content/renderer/input/input_handler_manager_client.h
index a65ad731cbd3b4c69be40d6d4374cae611ed3379..19e8d2f650683be769e3acdc3b722d5a880b5070 100644
--- a/content/renderer/input/input_handler_manager_client.h
+++ b/content/renderer/input/input_handler_manager_client.h
@@ -11,19 +11,17 @@
 #include "content/common/content_export.h"
 #include "content/common/input/input_event_ack_state.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
+#include "ui/events/blink/scoped_web_input_event.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 
-namespace ui {
-class LatencyInfo;
-struct DidOverscrollParams;
-}
-
 namespace cc {
 class InputHandler;
 }
 
 namespace ui {
+class LatencyInfo;
 class SynchronousInputHandlerProxy;
+struct DidOverscrollParams;
 }
 
 namespace content {
@@ -32,13 +30,19 @@ class CONTENT_EXPORT InputHandlerManagerClient {
  public:
   virtual ~InputHandlerManagerClient() {}
 
+  using InputEventAckStateCallback =
+      base::Callback<void(InputEventAckState,
+                          ui::ScopedWebInputEvent,
+                          const ui::LatencyInfo&,
+                          std::unique_ptr<ui::DidOverscrollParams>)>;
   // The Manager will supply a |handler| when bound to the client. This is valid
   // until the manager shuts down, at which point it supplies a null |handler|.
   // The client should only makes calls to |handler| on the compositor thread.
-  typedef base::Callback<
-      InputEventAckState(int /*routing_id*/,
-                         const blink::WebInputEvent*,
-                         ui::LatencyInfo* latency_info)> Handler;
+  using Handler =
+      base::Callback<void(int /*routing_id*/,
+                          ui::ScopedWebInputEvent,
+                          const ui::LatencyInfo& latency_info,
+                          const InputEventAckStateCallback& callback)>;
 
   // Called from the main thread.
   virtual void SetBoundHandler(const Handler& handler) = 0;
@@ -50,7 +54,8 @@ class CONTENT_EXPORT InputHandlerManagerClient {
   virtual void RegisterRoutingID(int routing_id) = 0;
   virtual void UnregisterRoutingID(int routing_id) = 0;
   virtual void DidOverscroll(int routing_id,
-                             const ui::DidOverscrollParams& params) = 0;
+                             const ui::DidOverscrollParams& params,
+                             bool bundle_ack_with_triggering_event) = 0;
   virtual void DidStartFlinging(int routing_id) = 0;
   virtual void DidStopFlinging(int routing_id) = 0;