Change the InputEventAck codepath to use a tri-state-enum instead of a boolean

Right now whenever an input event ACK is sent back to render_widget_host_impl we do
not distinguish between events that are returned because they didn't hit any touch event handlers vs events not handled by touch event handler when there is a hit.
This change adds a tri-state enum to the IPC message that will be used
to distinguish NotProcessed touch events from Returned touch events.

BUG=135818

Review URL: https://chromiumcodereview.appspot.com/11363133

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170304 0039d316-1c4b-4281-b951-d872f2087c98

29 files changed, 122 insertions, 62 deletions

diff --git a/content/DEPS b/content/DEPS
index db04ce4..09dd65b 100644
--- a/content/DEPS
+++ b/content/DEPS
@@ -9,6 +9,7 @@ include_rules = [
   # directories in content/ so we disallow all of them.
   "-content",
   "+content/common",
+  "+content/port/common",
   "+content/public/common",
   "+content/public/test",
   "+content/shell",  # for content_browsertests
diff --git a/content/browser/android/content_view_core_impl.cc b/content/browser/android/content_view_core_impl.cc
index 2cefc27..e6d2d8e 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -470,12 +470,13 @@ void ContentViewCoreImpl::ShowSelectPopupMenu(
                                        multiple, selected_array.obj());
 }
 
-void ContentViewCoreImpl::ConfirmTouchEvent(bool handled) {
+void ContentViewCoreImpl::ConfirmTouchEvent(InputEventAckState ack_result) {
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobject> j_obj = java_ref_.get(env);
   if (j_obj.is_null())
     return;
-  Java_ContentViewCore_confirmTouchEvent(env, j_obj.obj(), handled);
+  bool processed = (ack_result == INPUT_EVENT_ACK_STATE_CONSUMED);
+  Java_ContentViewCore_confirmTouchEvent(env, j_obj.obj(), processed);
 }
 
 void ContentViewCoreImpl::HasTouchEventHandlers(bool need_touch_events) {
diff --git a/content/browser/android/content_view_core_impl.h b/content/browser/android/content_view_core_impl.h
index 8311484..ed307ca 100644
--- a/content/browser/android/content_view_core_impl.h
+++ b/content/browser/android/content_view_core_impl.h
@@ -215,7 +215,7 @@ class ContentViewCoreImpl : public ContentViewCore,
   void SetTitle(const string16& title);
 
   bool HasFocus();
-  void ConfirmTouchEvent(bool handled);
+  void ConfirmTouchEvent(InputEventAckState ack_result);
   void HasTouchEventHandlers(bool need_touch_events);
   void OnSelectionChanged(const std::string& text);
   void OnSelectionBoundsChanged(
diff --git a/content/browser/browser_plugin/browser_plugin_guest_helper.cc b/content/browser/browser_plugin/browser_plugin_guest_helper.cc
index b1de4d9..abd2c14 100644
--- a/content/browser/browser_plugin/browser_plugin_guest_helper.cc
+++ b/content/browser/browser_plugin/browser_plugin_guest_helper.cc
@@ -51,8 +51,9 @@ void BrowserPluginGuestHelper::OnUpdateRect(
 
 void BrowserPluginGuestHelper::OnHandleInputEventAck(
     WebKit::WebInputEvent::Type event_type,
-    bool processed) {
-  guest_->HandleInputEventAck(render_view_host(), processed);
+    InputEventAckState ack_result) {
+  guest_->HandleInputEventAck(render_view_host(),
+                              ack_result == INPUT_EVENT_ACK_STATE_CONSUMED);
 }
 
 void BrowserPluginGuestHelper::OnTakeFocus(bool reverse) {
diff --git a/content/browser/browser_plugin/browser_plugin_guest_helper.h b/content/browser/browser_plugin/browser_plugin_guest_helper.h
index d7ead1d..ea5c536 100644
--- a/content/browser/browser_plugin/browser_plugin_guest_helper.h
+++ b/content/browser/browser_plugin/browser_plugin_guest_helper.h
@@ -5,6 +5,7 @@
 #ifndef CONTENT_BROWSER_BROWSER_PLUGIN_BROWSER_PLUGIN_GUEST_HELPER_H_
 #define CONTENT_BROWSER_BROWSER_PLUGIN_BROWSER_PLUGIN_GUEST_HELPER_H_
 
+#include "content/port/common/input_event_ack_state.h"
 #include "content/public/browser/render_view_host_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebDragOperation.h"
@@ -46,7 +47,7 @@ class BrowserPluginGuestHelper : public RenderViewHostObserver {
   void OnUpdateDragCursor(WebKit::WebDragOperation current_op);
   void OnUpdateRect(const ViewHostMsg_UpdateRect_Params& params);
   void OnHandleInputEventAck(WebKit::WebInputEvent::Type event_type,
-                             bool processed);
+                             InputEventAckState ack_result);
   void OnTakeFocus(bool reverse);
   void OnShowWidget(int route_id, const gfx::Rect& initial_pos);
   void OnMsgHasTouchEventHandlers(bool has_handlers);
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index a2a664b..7ca455b 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -1112,7 +1112,7 @@ void RenderWidgetHostImpl::ForwardInputEvent(const WebInputEvent& input_event,
       // to the touch-event queue immediately. Mark the event as not processed,
       // to make sure that the touch-scroll gesture that initiated the
       // overscroll is updated properly.
-      touch_event_queue_->ProcessTouchAck(false);
+      touch_event_queue_->ProcessTouchAck(INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
     }
     return;
   }
@@ -1676,9 +1676,11 @@ void RenderWidgetHostImpl::DidUpdateBackingStore(
       "x+y", params.bitmap_rect.x() + params.bitmap_rect.y());
 }
 
-void RenderWidgetHostImpl::OnMsgInputEventAck(WebInputEvent::Type event_type,
-                                              bool processed) {
+void RenderWidgetHostImpl::OnMsgInputEventAck(
+    WebInputEvent::Type event_type, InputEventAckState ack_result) {
   TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::OnMsgInputEventAck");
+  bool processed = (ack_result == INPUT_EVENT_ACK_STATE_CONSUMED);
+
   if (!in_process_event_types_.empty() &&
       in_process_event_types_.front() == event_type)
     in_process_event_types_.pop();
@@ -1714,7 +1716,7 @@ void RenderWidgetHostImpl::OnMsgInputEventAck(WebInputEvent::Type event_type,
   } else if (type == WebInputEvent::MouseWheel) {
     ProcessWheelAck(processed);
   } else if (WebInputEvent::isTouchEventType(type)) {
-    ProcessTouchAck(processed);
+    ProcessTouchAck(ack_result);
   } else if (WebInputEvent::isGestureEventType(type)) {
     ProcessGestureAck(processed, type);
   }
@@ -1854,8 +1856,8 @@ void RenderWidgetHostImpl::ProcessGestureAck(bool processed, int type) {
   gesture_event_filter_->ProcessGestureAck(processed, type);
 }
 
-void RenderWidgetHostImpl::ProcessTouchAck(bool processed) {
-  touch_event_queue_->ProcessTouchAck(processed);
+void RenderWidgetHostImpl::ProcessTouchAck(InputEventAckState ack_result) {
+  touch_event_queue_->ProcessTouchAck(ack_result);
 }
 
 void RenderWidgetHostImpl::OnMsgFocus() {
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index fe67ebd..b2dbae7 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -22,6 +22,7 @@
 #include "base/timer.h"
 #include "build/build_config.h"
 #include "content/common/view_message_enums.h"
+#include "content/port/common/input_event_ack_state.h"
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/common/page_zoom.h"
 #include "ipc/ipc_listener.h"
@@ -573,7 +574,7 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   void OnMsgUpdateRect(const ViewHostMsg_UpdateRect_Params& params);
   void OnMsgUpdateIsDelayed();
   void OnMsgInputEventAck(WebKit::WebInputEvent::Type event_type,
-                          bool processed);
+                          InputEventAckState ack_result);
   void OnMsgBeginSmoothScroll(
       int gesture_id,
       const ViewHostMsg_BeginSmoothScroll_Params &params);
@@ -679,7 +680,7 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   // Called on OnMsgInputEventAck() to process a touch event ack message.
   // This can result in a gesture event being generated and sent back to the
   // renderer.
-  void ProcessTouchAck(bool processed);
+  void ProcessTouchAck(InputEventAckState ack_result);
 
   // Called when there is a new auto resize (using a post to avoid a stack
   // which may get in recursive loops).
diff --git a/content/browser/renderer_host/render_widget_host_unittest.cc b/content/browser/renderer_host/render_widget_host_unittest.cc
index 2cd5503..1ada7c6 100644
--- a/content/browser/renderer_host/render_widget_host_unittest.cc
+++ b/content/browser/renderer_host/render_widget_host_unittest.cc
@@ -344,7 +344,7 @@ class TestView : public TestRenderWidgetHostView {
     return bounds_;
   }
   virtual void ProcessAckedTouchEvent(const WebTouchEvent& touch,
-                                      bool processed) OVERRIDE {
+                                      InputEventAckState ack_result) OVERRIDE {
     acked_event_ = touch;
     ++acked_event_count_;
   }
@@ -493,8 +493,10 @@ class RenderWidgetHostTest : public testing::Test {
   }
 
   void SendInputEventACK(WebInputEvent::Type type, bool processed) {
+    InputEventAckState ack_result = processed ?
+        INPUT_EVENT_ACK_STATE_CONSUMED : INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
     scoped_ptr<IPC::Message> response(
-        new ViewHostMsg_HandleInputEvent_ACK(0, type, processed));
+        new ViewHostMsg_HandleInputEvent_ACK(0, type, ack_result));
     host_->OnMessageReceived(*response);
   }
 
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index 97d4244..0c55f7d 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -463,10 +463,9 @@ void RenderWidgetHostViewAndroid::UnhandledWheelEvent(
 }
 
 void RenderWidgetHostViewAndroid::ProcessAckedTouchEvent(
-    const WebKit::WebTouchEvent& touch_event,
-    bool processed) {
+    const WebKit::WebTouchEvent& touch_event, InputEventAckState ack_result) {
   if (content_view_core_)
-    content_view_core_->ConfirmTouchEvent(processed);
+    content_view_core_->ConfirmTouchEvent(ack_result);
 }
 
 void RenderWidgetHostViewAndroid::SetHasHorizontalScrollbar(
diff --git a/content/browser/renderer_host/render_widget_host_view_android.h b/content/browser/renderer_host/render_widget_host_view_android.h
index 8394d58..205c8d7 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.h
+++ b/content/browser/renderer_host/render_widget_host_view_android.h
@@ -111,7 +111,7 @@ class RenderWidgetHostViewAndroid : public RenderWidgetHostViewBase {
   virtual void UnhandledWheelEvent(
       const WebKit::WebMouseWheelEvent& event) OVERRIDE;
   virtual void ProcessAckedTouchEvent(const WebKit::WebTouchEvent& touch,
-                                      bool processed) OVERRIDE;
+                                      InputEventAckState ack_result) OVERRIDE;
   virtual void SetHasHorizontalScrollbar(
       bool has_horizontal_scrollbar) OVERRIDE;
   virtual void SetScrollOffsetPinning(
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 25b37f00..e742266 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -1048,8 +1048,7 @@ gfx::Rect RenderWidgetHostViewAura::GetBoundsInRootWindow() {
 }
 
 void RenderWidgetHostViewAura::ProcessAckedTouchEvent(
-    const WebKit::WebTouchEvent& touch_event,
-    bool processed) {
+    const WebKit::WebTouchEvent& touch_event, InputEventAckState ack_result) {
   ScopedVector<ui::TouchEvent> events;
   if (!MakeUITouchEventsFromWebTouchEvents(touch_event, &events))
     return;
@@ -1059,7 +1058,8 @@ void RenderWidgetHostViewAura::ProcessAckedTouchEvent(
   if (!root)
     return;
 
-  ui::EventResult result = processed ? ui::ER_HANDLED : ui::ER_UNHANDLED;
+  ui::EventResult result = (ack_result ==
+      INPUT_EVENT_ACK_STATE_CONSUMED) ? ui::ER_HANDLED : ui::ER_UNHANDLED;
   for (ScopedVector<ui::TouchEvent>::iterator iter = events.begin(),
       end = events.end(); iter != end; ++iter) {
     root->ProcessedTouchEvent((*iter), window_, result);
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.h b/content/browser/renderer_host/render_widget_host_view_aura.h
index d46251e..d3bfd54 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -128,8 +128,9 @@ class RenderWidgetHostViewAura
   virtual void AcceleratedSurfaceRelease(uint64 surface_id) OVERRIDE;
   virtual void GetScreenInfo(WebKit::WebScreenInfo* results) OVERRIDE;
   virtual gfx::Rect GetBoundsInRootWindow() OVERRIDE;
-  virtual void ProcessAckedTouchEvent(const WebKit::WebTouchEvent& touch,
-                                      bool processed) OVERRIDE;
+  virtual void ProcessAckedTouchEvent(
+      const WebKit::WebTouchEvent& touch,
+      InputEventAckState ack_result) OVERRIDE;
   virtual void SetHasHorizontalScrollbar(
       bool has_horizontal_scrollbar) OVERRIDE;
   virtual void SetScrollOffsetPinning(
diff --git a/content/browser/renderer_host/render_widget_host_view_base.cc b/content/browser/renderer_host/render_widget_host_view_base.cc
index 68404f8..51e530a 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.cc
+++ b/content/browser/renderer_host/render_widget_host_view_base.cc
@@ -480,8 +480,7 @@ SmoothScrollGesture* RenderWidgetHostViewBase::CreateSmoothScrollGesture(
 }
 
 void RenderWidgetHostViewBase::ProcessAckedTouchEvent(
-    const WebKit::WebTouchEvent& touch,
-    bool processed) {
+    const WebKit::WebTouchEvent& touch, InputEventAckState ack_result) {
 }
 
 }  // namespace content
diff --git a/content/browser/renderer_host/render_widget_host_view_base.h b/content/browser/renderer_host/render_widget_host_view_base.h
index b884b5f..b202f96 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.h
+++ b/content/browser/renderer_host/render_widget_host_view_base.h
@@ -60,7 +60,7 @@ class CONTENT_EXPORT RenderWidgetHostViewBase
   virtual BrowserAccessibilityManager*
       GetBrowserAccessibilityManager() const OVERRIDE;
   virtual void ProcessAckedTouchEvent(const WebKit::WebTouchEvent& touch,
-                                      bool processed) OVERRIDE;
+                                      InputEventAckState ack_result) OVERRIDE;
   virtual SmoothScrollGesture* CreateSmoothScrollGesture(
       bool scroll_down, int pixels_to_scroll, int mouse_event_x,
       int mouse_event_y) OVERRIDE;
diff --git a/content/browser/renderer_host/render_widget_host_view_win.cc b/content/browser/renderer_host/render_widget_host_view_win.cc
index e42bbac..eb25310 100644
--- a/content/browser/renderer_host/render_widget_host_view_win.cc
+++ b/content/browser/renderer_host/render_widget_host_view_win.cc
@@ -815,15 +815,15 @@ void RenderWidgetHostViewWin::SetBackground(const SkBitmap& background) {
 }
 
 void RenderWidgetHostViewWin::ProcessAckedTouchEvent(
-    const WebKit::WebTouchEvent& touch,
-    bool processed) {
+    const WebKit::WebTouchEvent& touch, InputEventAckState ack_result) {
   DCHECK(touch_events_enabled_);
 
   ScopedVector<ui::TouchEvent> events;
   if (!MakeUITouchEventsFromWebTouchEvents(touch, &events))
     return;
 
-  ui::EventResult result = processed ? ui::ER_HANDLED : ui::ER_UNHANDLED;
+  ui::EventResult result = (ack_result ==
+      INPUT_EVENT_ACK_STATE_CONSUMED) ? ui::ER_HANDLED : ui::ER_UNHANDLED;
   for (ScopedVector<ui::TouchEvent>::iterator iter = events.begin(),
       end = events.end(); iter != end; ++iter)  {
     scoped_ptr<ui::GestureRecognizer::Gestures> gestures;
diff --git a/content/browser/renderer_host/render_widget_host_view_win.h b/content/browser/renderer_host/render_widget_host_view_win.h
index 2ebbcdf..27ef42a 100644
--- a/content/browser/renderer_host/render_widget_host_view_win.h
+++ b/content/browser/renderer_host/render_widget_host_view_win.h
@@ -202,7 +202,7 @@ class RenderWidgetHostViewWin
       skia::PlatformBitmap* output) OVERRIDE;
   virtual void OnAcceleratedCompositingStateChange() OVERRIDE;
   virtual void ProcessAckedTouchEvent(const WebKit::WebTouchEvent& touch,
-                                      bool processed) OVERRIDE;
+                                      InputEventAckState ack_result) OVERRIDE;
   virtual void SetHasHorizontalScrollbar(
       bool has_horizontal_scrollbar) OVERRIDE;
   virtual void SetScrollOffsetPinning(
diff --git a/content/browser/renderer_host/touch_event_queue.cc b/content/browser/renderer_host/touch_event_queue.cc
index a9ceedb..178dfde 100644
--- a/content/browser/renderer_host/touch_event_queue.cc
+++ b/content/browser/renderer_host/touch_event_queue.cc
@@ -105,8 +105,8 @@ void TouchEventQueue::QueueEvent(const WebKit::WebTouchEvent& event) {
   touch_queue_.push_back(new CoalescedWebTouchEvent(event));
 }
 
-void TouchEventQueue::ProcessTouchAck(bool processed) {
-  PopTouchEventToView(processed);
+void TouchEventQueue::ProcessTouchAck(InputEventAckState ack_result) {
+  PopTouchEventToView(ack_result);
   // If there's a queued touch-event, then forward it to the renderer now.
   if (!touch_queue_.empty()) {
     render_widget_host_->ForwardTouchEventImmediately(
@@ -116,7 +116,7 @@ void TouchEventQueue::ProcessTouchAck(bool processed) {
 
 void TouchEventQueue::FlushQueue() {
   while (!touch_queue_.empty())
-    PopTouchEventToView(false);
+    PopTouchEventToView(INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
 }
 
 void TouchEventQueue::Reset() {
@@ -131,7 +131,7 @@ const WebKit::WebTouchEvent& TouchEventQueue::GetLatestEvent() const {
   return touch_queue_.back()->coalesced_event();
 }
 
-void TouchEventQueue::PopTouchEventToView(bool processed) {
+void TouchEventQueue::PopTouchEventToView(InputEventAckState ack_result) {
   if (touch_queue_.empty())
     return;
   scoped_ptr<CoalescedWebTouchEvent> acked_event(touch_queue_.front());
@@ -144,7 +144,7 @@ void TouchEventQueue::PopTouchEventToView(bool processed) {
   for (WebTouchEventList::const_iterator iter = acked_event->begin(),
        end = acked_event->end();
        iter != end; ++iter) {
-    view->ProcessAckedTouchEvent((*iter), processed);
+    view->ProcessAckedTouchEvent((*iter), ack_result);
   }
 }
 
diff --git a/content/browser/renderer_host/touch_event_queue.h b/content/browser/renderer_host/touch_event_queue.h
index 6a817d4..bd23a7f 100644
--- a/content/browser/renderer_host/touch_event_queue.h
+++ b/content/browser/renderer_host/touch_event_queue.h
@@ -9,6 +9,7 @@
 
 #include "base/basictypes.h"
 #include "content/common/content_export.h"
+#include "content/port/common/input_event_ack_state.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebInputEvent.h"
 
 namespace content {
@@ -32,7 +33,7 @@ class TouchEventQueue {
   // Notifies the queue that a touch-event has been processed by the renderer.
   // At this point, the queue may send one or more gesture events and/or
   // additional queued touch-events to the renderer.
-  void ProcessTouchAck(bool processed);
+  void ProcessTouchAck(InputEventAckState ack_result);
 
   // Empties the queue of touch events. This may result in any number of gesture
   // events being sent to the renderer.
@@ -55,7 +56,7 @@ class TouchEventQueue {
 
   // Pops the touch-event from the top of the queue and sends it to the
   // RenderWidgetHostView. This reduces the size of the queue by one.
-  void PopTouchEventToView(bool processed);
+  void PopTouchEventToView(InputEventAckState ack_result);
 
   // The RenderWidgetHost that owns this event-queue.
   RenderWidgetHostImpl* render_widget_host_;
diff --git a/content/common/view_messages.h b/content/common/view_messages.h
index 507b9e7..c2c6dcd 100644
--- a/content/common/view_messages.h
+++ b/content/common/view_messages.h
@@ -13,6 +13,7 @@
 #include "content/common/edit_command.h"
 #include "content/common/navigation_gesture.h"
 #include "content/common/view_message_enums.h"
+#include "content/port/common/input_event_ack_state.h"
 #include "content/public/common/common_param_traits.h"
 #include "content/public/common/context_menu_params.h"
 #include "content/public/common/file_chooser_params.h"
@@ -71,6 +72,7 @@ IPC_ENUM_TRAITS(WebKit::WebTextDirection)
 IPC_ENUM_TRAITS(WebMenuItem::Type)
 IPC_ENUM_TRAITS(WindowContainerType)
 IPC_ENUM_TRAITS(content::FileChooserParams::Mode)
+IPC_ENUM_TRAITS(content::InputEventAckState)
 IPC_ENUM_TRAITS(content::JavaScriptMessageType)
 IPC_ENUM_TRAITS(content::NavigationGesture)
 IPC_ENUM_TRAITS(content::PageZoom)
@@ -1734,7 +1736,7 @@ IPC_MESSAGE_ROUTED1(ViewHostMsg_DidActivateAcceleratedCompositing,
 // Acknowledges receipt of a ViewMsg_HandleInputEvent message.
 IPC_MESSAGE_ROUTED2(ViewHostMsg_HandleInputEvent_ACK,
                     WebKit::WebInputEvent::Type,
-                    bool /* processed */)
+                    content::InputEventAckState /* ack_result */)
 
 IPC_STRUCT_BEGIN(ViewHostMsg_BeginSmoothScroll_Params)
   IPC_STRUCT_MEMBER(bool, scroll_down)
diff --git a/content/content_common.gypi b/content/content_common.gypi
index 504aedf..a1a6a1d 100644
--- a/content/content_common.gypi
+++ b/content/content_common.gypi
@@ -375,6 +375,7 @@
     'common/webmessageportchannel_impl.h',
     'common/worker_messages.h',
     'common/zygote_commands_linux.h',
+    'port/common/input_event_ack_state.h',
     'public/common/common_param_traits.cc',
     'public/common/common_param_traits.h',
     'public/common/common_param_traits_macros.h',
diff --git a/content/port/browser/render_widget_host_view_port.h b/content/port/browser/render_widget_host_view_port.h
index b09e22a..6d4806a 100644
--- a/content/port/browser/render_widget_host_view_port.h
+++ b/content/port/browser/render_widget_host_view_port.h
@@ -9,6 +9,7 @@
 #include "base/process_util.h"
 #include "base/string16.h"
 #include "content/common/content_export.h"
+#include "content/port/common/input_event_ack_state.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebPopupType.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebTextDirection.h"
@@ -269,10 +270,10 @@ class CONTENT_EXPORT RenderWidgetHostViewPort : public RenderWidgetHostView {
   // Because the associated remote WebKit instance can asynchronously
   // prevent-default on a dispatched touch event, the touch events are queued in
   // the GestureRecognizer until invocation of ProcessAckedTouchEvent releases
-  // it to be processed (when |processed| is false) or ignored (when |processed|
-  // is true).
+  // it to be consumed (when |ack_result| is NOT_CONSUMED OR NO_CONSUMER_EXISTS)
+  // or ignored (when |ack_result| is CONSUMED).
   virtual void ProcessAckedTouchEvent(const WebKit::WebTouchEvent& touch,
-                                      bool processed) = 0;
+                                      InputEventAckState ack_result) = 0;
 
   // Asks the view to create a smooth scroll gesture that will be used to
   // simulate a user-initiated scroll.
diff --git a/content/port/common/input_event_ack_state.h b/content/port/common/input_event_ack_state.h
new file mode 100644
index 0000000..77a1363
--- /dev/null
+++ b/content/port/common/input_event_ack_state.h
@@ -0,0 +1,19 @@
+// Copyright (c) 2012 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.
+
+#ifndef CONTENT_PORT_COMMON_INPUT_EVENT_ACK_STATE_H_
+#define CONTENT_PORT_COMMON_INPUT_EVENT_ACK_STATE_H_
+
+namespace content {
+
+// Describes the state of the input event ACK coming back to the browser side.
+enum InputEventAckState {
+  INPUT_EVENT_ACK_STATE_CONSUMED,
+  INPUT_EVENT_ACK_STATE_NOT_CONSUMED,
+  INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS,
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PORT_COMMON_INPUT_EVENT_ACK_STATE_H_
diff --git a/content/renderer/gpu/input_event_filter.cc b/content/renderer/gpu/input_event_filter.cc
index e2c885d..df1abf3 100644
--- a/content/renderer/gpu/input_event_filter.cc
+++ b/content/renderer/gpu/input_event_filter.cc
@@ -38,8 +38,7 @@ void InputEventFilter::RemoveRoute(int routing_id) {
 void InputEventFilter::DidHandleInputEvent() {
   DCHECK(target_loop_->BelongsToCurrentThread());
 
-  bool processed = true;
-  SendACK(messages_.front(), processed);
+  SendACK(messages_.front(), INPUT_EVENT_ACK_STATE_CONSUMED);
   messages_.pop();
 }
 
@@ -56,8 +55,7 @@ void InputEventFilter::DidNotHandleInputEvent(bool send_to_widget) {
                    this, messages_.front()));
   } else {
     TRACE_EVENT0("InputEventFilter::DidNotHandleInputEvent", "LeaveUnhandled");
-    bool processed = false;
-    SendACK(messages_.front(), processed);
+    SendACK(messages_.front(), INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS);
   }
   messages_.pop();
 }
@@ -130,25 +128,28 @@ void InputEventFilter::ForwardToHandler(const IPC::Message& message) {
   handler_.Run(message.routing_id(), CrackMessage(message));
 }
 
-void InputEventFilter::SendACK(const IPC::Message& message, bool processed) {
+void InputEventFilter::SendACK(const IPC::Message& message,
+                               InputEventAckState ack_result) {
   DCHECK(target_loop_->BelongsToCurrentThread());
 
   io_loop_->PostTask(
       FROM_HERE,
       base::Bind(&InputEventFilter::SendACKOnIOThread, this,
-                 message.routing_id(), CrackMessage(message)->type, processed));
+                 message.routing_id(), CrackMessage(message)->type,
+                 ack_result));
 }
 
-void InputEventFilter::SendACKOnIOThread(int routing_id,
-                                         WebInputEvent::Type event_type,
-                                         bool processed) {
+void InputEventFilter::SendACKOnIOThread(
+    int routing_id,
+    WebInputEvent::Type event_type,
+    InputEventAckState ack_result) {
   DCHECK(io_loop_->BelongsToCurrentThread());
 
   if (!sender_)
     return;  // Filter was removed.
 
   sender_->Send(
-      new ViewHostMsg_HandleInputEvent_ACK(routing_id, event_type, processed));
+      new ViewHostMsg_HandleInputEvent_ACK(routing_id, event_type, ack_result));
 }
 
 }  // namespace content
diff --git a/content/renderer/gpu/input_event_filter.h b/content/renderer/gpu/input_event_filter.h
index eaf6050..690e9bd 100644
--- a/content/renderer/gpu/input_event_filter.h
+++ b/content/renderer/gpu/input_event_filter.h
@@ -11,6 +11,7 @@
 #include "base/callback_forward.h"
 #include "base/synchronization/lock.h"
 #include "content/common/content_export.h"
+#include "content/port/common/input_event_ack_state.h"
 #include "ipc/ipc_channel_proxy.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebInputEvent.h"
 
@@ -70,9 +71,9 @@ class CONTENT_EXPORT InputEventFilter
 
   void ForwardToMainListener(const IPC::Message& message);
   void ForwardToHandler(const IPC::Message& message);
-  void SendACK(const IPC::Message& message, bool processed);
+  void SendACK(const IPC::Message& message, InputEventAckState ack_result);
   void SendACKOnIOThread(int routing_id, WebKit::WebInputEvent::Type event_type,
-                         bool processed);
+                         InputEventAckState ack_result);
 
   scoped_refptr<base::MessageLoopProxy> main_loop_;
   IPC::Listener* main_listener_;
diff --git a/content/renderer/gpu/input_event_filter_unittest.cc b/content/renderer/gpu/input_event_filter_unittest.cc
index aa65372..781560c 100644
--- a/content/renderer/gpu/input_event_filter_unittest.cc
+++ b/content/renderer/gpu/input_event_filter_unittest.cc
@@ -162,11 +162,11 @@ TEST(InputEventFilterTest, Basic) {
     EXPECT_EQ(ViewHostMsg_HandleInputEvent_ACK::ID, message->type());
 
     WebInputEvent::Type event_type = WebInputEvent::Undefined;
-    bool processed = false;
+    InputEventAckState ack_result = INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
     EXPECT_TRUE(ViewHostMsg_HandleInputEvent_ACK::Read(message, &event_type,
-                                                       &processed));
+                                                       &ack_result));
     EXPECT_EQ(kEvents[i].type, event_type);
-    EXPECT_FALSE(processed);
+    EXPECT_EQ(ack_result, INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS);
 
     const WebInputEvent* event = event_recorder.record_at(i);
     ASSERT_TRUE(event);
@@ -211,11 +211,11 @@ TEST(InputEventFilterTest, Basic) {
     EXPECT_EQ(ViewHostMsg_HandleInputEvent_ACK::ID, message->type());
 
     WebInputEvent::Type event_type = WebInputEvent::Undefined;
-    bool processed = false;
+    InputEventAckState ack_result = INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
     EXPECT_TRUE(ViewHostMsg_HandleInputEvent_ACK::Read(message, &event_type,
-                                                       &processed));
+                                                       &ack_result));
     EXPECT_EQ(kEvents[i].type, event_type);
-    EXPECT_TRUE(processed);
+    EXPECT_EQ(ack_result, INPUT_EVENT_ACK_STATE_CONSUMED);
   }
 
   filter->OnFilterRemoved();
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 5f1411c..6a5ca3c 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -5728,6 +5728,12 @@ void RenderViewImpl::DidHandleTouchEvent(const WebTouchEvent& event) {
   FOR_EACH_OBSERVER(RenderViewObserver, observers_, DidHandleTouchEvent(event));
 }
 
+bool RenderViewImpl::HasTouchEventHandlersAt(const gfx::Point& point) const {
+  if (!webview())
+    return false;
+  return webview()->hasTouchEventHandlersAt(point);
+}
+
 void RenderViewImpl::OnWasHidden() {
   RenderWidget::OnWasHidden();
 
diff --git a/content/renderer/render_view_impl.h b/content/renderer/render_view_impl.h
index ec3dcb4e..1c40767 100644
--- a/content/renderer/render_view_impl.h
+++ b/content/renderer/render_view_impl.h
@@ -761,6 +761,7 @@ class CONTENT_EXPORT RenderViewImpl
       const WebKit::WebGestureEvent& event) OVERRIDE;
   virtual void DidHandleMouseEvent(const WebKit::WebMouseEvent& event) OVERRIDE;
   virtual void DidHandleTouchEvent(const WebKit::WebTouchEvent& event) OVERRIDE;
+  virtual bool HasTouchEventHandlersAt(const gfx::Point& point) const OVERRIDE;
   virtual void OnSetFocus(bool enable) OVERRIDE;
   virtual void OnWasHidden() OVERRIDE;
   virtual void OnWasShown(bool needs_repainting) OVERRIDE;
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index b09cc01..2b42bc2 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -590,9 +590,19 @@ void RenderWidget::OnHandleInputEvent(const IPC::Message& message) {
   if (!processed && is_keyboard_shortcut)
     suppress_next_char_events_ = true;
 
+  InputEventAckState ack_result = processed ?
+      INPUT_EVENT_ACK_STATE_CONSUMED : INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
+  if (!processed &&  input_event->type == WebInputEvent::TouchStart) {
+    const WebTouchEvent& touch_event =
+        *static_cast<const WebTouchEvent*>(input_event);
+    ack_result = HasTouchEventHandlersAt(touch_event.touches[0].position) ?
+        INPUT_EVENT_ACK_STATE_NOT_CONSUMED :
+        INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS;
+  }
+
   IPC::Message* response =
       new ViewHostMsg_HandleInputEvent_ACK(routing_id_, input_event->type,
-                                           processed);
+                                           ack_result);
   bool event_type_gets_rate_limited =
       input_event->type == WebInputEvent::MouseMove ||
       input_event->type == WebInputEvent::MouseWheel ||
@@ -1968,4 +1978,8 @@ bool RenderWidget::WebWidgetHandlesCompositorScheduling() const {
   return false;
 }
 
+bool RenderWidget::HasTouchEventHandlersAt(const gfx::Point& point) const {
+  return true;
+}
+
 }  // namespace content
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index 11a0937..b194ca5 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -45,6 +45,7 @@ namespace WebKit {
 class WebGestureEvent;
 class WebMouseEvent;
 struct WebRenderingStatsImpl;
+struct WebPoint;
 class WebTouchEvent;
 }
 
@@ -430,6 +431,10 @@ class CONTENT_EXPORT RenderWidget
   // just handled.
   virtual void DidHandleTouchEvent(const WebKit::WebTouchEvent& event) {}
 
+  // Check whether the WebWidget has any touch event handlers registered
+  // at the given point.
+  virtual bool HasTouchEventHandlersAt(const gfx::Point& point) const;
+
   // Should return true if the underlying WebWidget is responsible for
   // the scheduling of compositing requests.
   virtual bool WebWidgetHandlesCompositorScheduling() const;