Move fling implementation from renderer to browser:

content/browser/renderer_host/input/immediate_input_router.cc

Index: content/browser/renderer_host/input/immediate_input_router.cc
diff --git a/content/browser/renderer_host/input/immediate_input_router.cc b/content/browser/renderer_host/input/immediate_input_router.cc
index 06bbc950e1d798a648fac65502f6c1c57365badc..31876bde5e022ce15a48ed80af25957db152174c 100644
--- a/content/browser/renderer_host/input/immediate_input_router.cc
+++ b/content/browser/renderer_host/input/immediate_input_router.cc
@@ -70,8 +70,73 @@ const char* GetEventAckName(InputEventAckState ack_result) {
   return "";
 }
 
+bool BrowserSideFlingEnabled() {
+  return CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableBrowserSideFling);
+}
+
 } // namespace
 
+// A helper class that based on the value of the |kEnableBrowserSideFling| flag
+// does event filtering using either |BaseGestureEventFilter| or
+// |GestureEventFilter|.
+class ImmediateInputRouter::EventFilteringHelper {
+ public:
+  // |router| must outlive us.
+  explicit EventFilteringHelper(ImmediateInputRouter* router) {
+    if (BrowserSideFlingEnabled())
+      gesture_event_filter_.reset(new BaseGestureEventFilter(router));
+    else
+      gesture_event_filter_.reset(new GestureEventFilter(router, router));
+  }
+  virtual ~EventFilteringHelper() {}
+
+  bool ShouldDeferMouseDown(const MouseEventWithLatencyInfo& mouse_event) {
+    if (BrowserSideFlingEnabled())
+      return false;
+
+    return static_cast<GestureEventFilter*>(gesture_event_filter_.get())->
+        GetTouchpadTapSuppressionController()->ShouldDeferMouseDown(
+            mouse_event);
+  }
+
+  bool ShouldDeferMouseUp(const MouseEventWithLatencyInfo& mouse_event) {
+    if (BrowserSideFlingEnabled())
+      return false;
+
+    return static_cast<GestureEventFilter*>(gesture_event_filter_.get())->
+        GetTouchpadTapSuppressionController()->ShouldSuppressMouseUp();
+  }
+
+  void FlingHasBeenHalted() {
+    if (BrowserSideFlingEnabled())
+      return;
+
+    static_cast<GestureEventFilter*>(gesture_event_filter_.get())->
+        FlingHasBeenHalted();
+  }
+
+  bool ShouldForwardGesture(const GestureEventWithLatencyInfo& gesture_event) {
+    return gesture_event_filter_->ShouldForward(gesture_event);
+  }
+
+  bool HasQueuedGestureEvents() {
+    return gesture_event_filter_->HasQueuedGestureEvents();
+  }
+
+  void ProcessGestureAck(InputEventAckState ack_result,
+                         blink::WebInputEvent::Type type,
+                         const ui::LatencyInfo& latency) {
+    gesture_event_filter_->ProcessGestureAck(ack_result, type, latency);
+  }
+
+ private:
+  friend class ImmediateInputRouter;
+  scoped_ptr<BaseGestureEventFilter> gesture_event_filter_;
+
+  DISALLOW_COPY_AND_ASSIGN(EventFilteringHelper);
+};
+
 ImmediateInputRouter::ImmediateInputRouter(IPC::Sender* sender,
                                            InputRouterClient* client,
                                            InputAckHandler* ack_handler,
@@ -87,7 +152,8 @@ ImmediateInputRouter::ImmediateInputRouter(IPC::Sender* sender,
       has_touch_handler_(false),
       current_ack_source_(ACK_SOURCE_NONE),
       touch_event_queue_(new TouchEventQueue(this)),
-      gesture_event_filter_(new GestureEventFilter(this, this)) {
+      flinger_(new Flinger(this)),
+      event_filter_(new EventFilteringHelper(this)) {
   DCHECK(sender);
   DCHECK(client);
   DCHECK(ack_handler);
@@ -126,13 +192,14 @@ void ImmediateInputRouter::SendMouseEvent(
     return;
   }
 
+  if (BrowserSideFlingEnabled() && flinger_->HandleMouseEvent(mouse_event))
+    return;
+
   if (mouse_event.event.type == WebInputEvent::MouseDown &&
-      gesture_event_filter_->GetTouchpadTapSuppressionController()->
-          ShouldDeferMouseDown(mouse_event))
+      event_filter_->ShouldDeferMouseDown(mouse_event))
       return;
   if (mouse_event.event.type == WebInputEvent::MouseUp &&
-      gesture_event_filter_->GetTouchpadTapSuppressionController()->
-          ShouldSuppressMouseUp())
+      event_filter_->ShouldDeferMouseUp(mouse_event))
       return;
 
   SendMouseEventImmediately(mouse_event);
@@ -140,6 +207,9 @@ void ImmediateInputRouter::SendMouseEvent(
 
 void ImmediateInputRouter::SendWheelEvent(
     const MouseWheelEventWithLatencyInfo& wheel_event) {
+  if (BrowserSideFlingEnabled() && flinger_->HandleWheelEvent(wheel_event))
+    return;
+
   // If there's already a mouse wheel event waiting to be sent to the renderer,
   // add the new deltas to that event. Not doing so (e.g., by dropping the old
   // event, as for mouse moves) results in very slow scrolling on the Mac (on
@@ -166,13 +236,16 @@ void ImmediateInputRouter::SendKeyboardEvent(
     const NativeWebKeyboardEvent& key_event,
     const ui::LatencyInfo& latency_info,
     bool is_keyboard_shortcut) {
+  if (BrowserSideFlingEnabled() && flinger_->HandleKeyboardEvent())
+    return;
+
   // Put all WebKeyboardEvent objects in a queue since we can't trust the
   // renderer and we need to give something to the HandleKeyboardEvent
   // handler.
   key_queue_.push_back(key_event);
   HISTOGRAM_COUNTS_100("Renderer.KeyboardQueueSize", key_queue_.size());
 
-  gesture_event_filter_->FlingHasBeenHalted();
+  event_filter_->FlingHasBeenHalted();
 
   // Only forward the non-native portions of our event.
   FilterAndSendWebInputEvent(key_event, latency_info, is_keyboard_shortcut);
@@ -182,8 +255,11 @@ void ImmediateInputRouter::SendGestureEvent(
     const GestureEventWithLatencyInfo& gesture_event) {
   HandleGestureScroll(gesture_event);
 
+  if (BrowserSideFlingEnabled() && flinger_->HandleGestureEvent(gesture_event))
+    return;
+
   if (!IsInOverscrollGesture() &&
-      !gesture_event_filter_->ShouldForward(gesture_event)) {
+      !event_filter_->ShouldForwardGesture(gesture_event)) {
     OverscrollController* controller = client_->GetOverscrollController();
     if (controller)
       controller->DiscardingGestureEvent(gesture_event.event);
@@ -277,6 +353,25 @@ void ImmediateInputRouter::OnGestureEventAck(
   ack_handler_->OnGestureEventAck(event, ack_result);
 }
 
+void ImmediateInputRouter::SendEventForFling(
+    const blink::WebInputEvent& event) {
+  ui::LatencyInfo latency_info;
+  if (Send(new InputMsg_HandleInputEvent(
+      routing_id(), &event, latency_info, false)))
+    in_process_messages_sources_.push(MESSAGE_SOURCE_FLING);
+}
+
+void ImmediateInputRouter::FlingFinished(
+    blink::WebGestureEvent::SourceDevice source) {
+  if (source == blink::WebGestureEvent::Touchscreen) {
+    ui::LatencyInfo latency_info;
+    blink::WebGestureEvent synthetic_gesture;
+    synthetic_gesture.type = blink::WebInputEvent::GestureScrollEnd;
+    synthetic_gesture.sourceDevice = blink::WebGestureEvent::Touchscreen;
+    OfferToRenderer(synthetic_gesture, latency_info, false);
+  }
+}
+
 bool ImmediateInputRouter::SendSelectRange(scoped_ptr<IPC::Message> message) {
   DCHECK(message->type() == InputMsg_SelectRange::ID);
   if (select_range_pending_) {
@@ -358,7 +453,7 @@ bool ImmediateInputRouter::OfferToOverscrollController(
     const blink::WebGestureEvent& gesture_event =
         static_cast<const blink::WebGestureEvent&>(input_event);
     // An ACK is expected for the event, so mark it as consumed.
-    consumed = !gesture_event_filter_->ShouldForward(
+    consumed = !event_filter_->ShouldForwardGesture(
         GestureEventWithLatencyInfo(gesture_event, latency_info));
   }
 
@@ -408,6 +503,7 @@ bool ImmediateInputRouter::OfferToRenderer(const WebInputEvent& input_event,
   input_event_start_time_ = TimeTicks::Now();
   if (Send(new InputMsg_HandleInputEvent(
           routing_id(), &input_event, latency_info, is_keyboard_shortcut))) {
+    in_process_messages_sources_.push(MESSAGE_SOURCE_REGULAR);
     client_->IncrementInFlightEventCount();
     return true;
   }
@@ -422,6 +518,13 @@ void ImmediateInputRouter::OnInputEventAck(
   TimeDelta delta = TimeTicks::Now() - input_event_start_time_;
   UMA_HISTOGRAM_TIMES("MPArch.IIR_InputEventDelta", delta);
 
+  InputMessageSource source = in_process_messages_sources_.front();
+  in_process_messages_sources_.pop();
+  if (source == MESSAGE_SOURCE_FLING) {
+    flinger_->ProcessEventAck(event_type, ack_result, latency_info);
+    return;
+  }
+
   client_->DecrementInFlightEventCount();
 
   ProcessInputEventAck(event_type, ack_result, latency_info, RENDERER);
@@ -560,12 +663,12 @@ void ImmediateInputRouter::ProcessGestureAck(WebInputEvent::Type type,
   // If |ack_result| originated from the overscroll controller, only
   // feed |gesture_event_filter_| the ack if it was expecting one.
   if (current_ack_source_ == OVERSCROLL_CONTROLLER &&
-      !gesture_event_filter_->HasQueuedGestureEvents()) {
+      !event_filter_->HasQueuedGestureEvents()) {
     return;
   }
 
   // |gesture_event_filter_| will forward to OnGestureEventAck when appropriate.
-  gesture_event_filter_->ProcessGestureAck(ack_result, type, latency);
+  event_filter_->ProcessGestureAck(ack_result, type, latency);
 }
 
 void ImmediateInputRouter::ProcessTouchAck(
@@ -681,4 +784,8 @@ bool ImmediateInputRouter::IsInOverscrollGesture() const {
   return controller && controller->overscroll_mode() != OVERSCROLL_NONE;
 }
 
+BaseGestureEventFilter* ImmediateInputRouter::gesture_event_filter() {
+  return event_filter_->gesture_event_filter_.get();
+}
+
 }  // namespace content