touch-event queue: Add a touch-event queue for all platforms.

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 3a85551f0639f76aa70c08f41dcf72003b78c798..a421f0924025c3f2661ac50d32655fca9e672856 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -28,6 +28,7 @@
 #include "content/browser/renderer_host/render_widget_helper.h"
 #include "content/browser/renderer_host/render_widget_host_delegate.h"
 #include "content/browser/renderer_host/tap_suppression_controller.h"
+#include "content/browser/renderer_host/touch_event_queue.h"
 #include "content/common/accessibility_messages.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "content/common/view_messages.h"
@@ -149,6 +150,7 @@ RenderWidgetHostImpl::RenderWidgetHostImpl(RenderWidgetHostDelegate* delegate,
       has_touch_handler_(false),
       ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)),
       tick_active_smooth_scroll_gestures_task_posted_(false),
+      touch_event_queue_(new TouchEventQueue(this)),
       gesture_event_filter_(new GestureEventFilter(this)) {
   CHECK(delegate_);
   if (routing_id_ == MSG_ROUTING_NONE) {
@@ -940,6 +942,15 @@ void RenderWidgetHostImpl::ForwardGestureEvent(
   ForwardInputEvent(gesture_event, sizeof(WebGestureEvent), false);
 }
 
+void RenderWidgetHostImpl::ForwardTouchEventImmediately(
+    const WebKit::WebTouchEvent& touch_event) {
+  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::ForwardTouchEvent");
+  if (ignore_input_events_ || process_->IgnoreInputEvents())
+    return;
+
+  ForwardInputEvent(touch_event, sizeof(WebKit::WebTouchEvent), false);
+}
+
 void RenderWidgetHostImpl::ForwardGestureEventImmediately(
     const WebKit::WebGestureEvent& gesture_event) {
   if (ignore_input_events_ || process_->IgnoreInputEvents())
@@ -1047,12 +1058,7 @@ void RenderWidgetHostImpl::ForwardInputEvent(const WebInputEvent& input_event,
 
 void RenderWidgetHostImpl::ForwardTouchEvent(
     const WebKit::WebTouchEvent& touch_event) {
-  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::ForwardTouchEvent");
-  if (ignore_input_events_ || process_->IgnoreInputEvents())
-    return;
-
-  // TODO(sad): Do touch-event coalescing when appropriate.
-  ForwardInputEvent(touch_event, sizeof(WebKit::WebTouchEvent), false);
+  touch_event_queue_->QueueEvent(touch_event);

[aelias_OOO_until_Jul13, 2012/10/16 23:28:38]

RenderWidgetHost is not doing anything here except bouncing the event to the
queue.  And the "Immediately" method above makes an API that consistent with the
other kinds of events.

I'm thinking touch-event senders should be changed to talk directly to the
queue.  Then you wouldn't need to change RWH::ForwardTouchEvent.  Maybe RWH can
have a public getter method returning a pointer to the queue?

[sadrul, 2012/10/16 23:49:14]

I actually considered doing something similar at first. But I thought it would
be better to keep the interaction between RWHV and RWH mostly unchanged, and
hide the queueing from the different RWHVs.

The ForwardTouchEvent/Immediately pair of functions are meant to be similar to
the ForwardGestureEvent/Immediately pair of functions, which do similar things
(throttles/coalesces events as appropriate), so I feel like this is more
consistent. In these cases, ForwardXXXEvent is the real API, and the Immediately
version is supposed to be used by the TouchEventQueue/GestureEventFilter as
appropriate, but since it is not possible to expose these 'Immediately'
functions without exposing all of the other privates in RWH, they became part of
the public API.

(Arguably, ForwardWheelEvent can also be split into two to be similar since it
also does throttling/coalescing).

 }
 
 #if defined(TOOLKIT_GTK)
@@ -1734,8 +1740,7 @@ void RenderWidgetHostImpl::ProcessGestureAck(bool processed, int type) {
 }
 
 void RenderWidgetHostImpl::ProcessTouchAck(bool processed) {
-  if (view_)
-    view_->ProcessTouchAck(processed);
+  touch_event_queue_->ProcessTouchAck(processed);
 }
 
 void RenderWidgetHostImpl::OnMsgFocus() {