Don't send touch move to renderer while scrolling

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
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 0da585350faa3e1e3fd09dbd9c5df1c4a8cde9d5..37caa35fb588e12053073e97b1934c5b784117f5 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -60,6 +60,7 @@
 #include "ui/base/gestures/gesture_recognizer.h"
 #include "ui/base/hit_test.h"
 #include "ui/base/ime/input_method.h"
+#include "ui/base/ui_base_switches_util.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/compositor/layer.h"
 #include "ui/gfx/canvas.h"
@@ -2474,6 +2475,34 @@ void RenderWidgetHostViewAura::OnGestureEvent(ui::GestureEvent* event) {
     host_->ForwardGestureEvent(fling_cancel);
   }
 
+  if (switches::IsTouchCancelAfterScrollEnabled()) {

[Rick Byers, 2013/05/30 01:53:29]

This code should apply to windows (non-aura) as well (and perhaps there's even
some opportunity to share logic with Android).  So it probably doesn't belong in
an Aura specific file.  

I know you and Sadrul are discussing where best to put this - I'm not sure
myself which option I think is best.

[Yufeng Shen (Slow to review), 2013/05/30 22:34:38]

Moved the logic to render_widget_host_impl.cc

+    // When there is touch handler on the page, once scrolling is started,
+    // we send a touch cancel to the page, and stops forwarding touch moves to
+    // the renderer. This is to align with Chrome on Android behavior.
+    if (event->type() == ui::ET_GESTURE_SCROLL_UPDATE &&
+        host_->ShouldForwardTouchEvent() &&
+        !host_->scroll_update_in_progress()) {
+      host_->scroll_update_in_progress() = true;

[sadrul, 2013/05/30 02:44:16]

ew no

[Yufeng Shen (Slow to review), 2013/05/30 22:34:38]

Done.

+      // Insert a TouchCancel event.
+      WebKit::WebTouchEvent cancel_event;
+      cancel_event.type = WebKit::WebInputEvent::TouchCancel;
+      cancel_event.timeStampSeconds = event->time_stamp().InSecondsF();
+      int id = event->GetLowestTouchId();
+      if (id != -1) {
+        cancel_event.touchesLength = 1;
+        cancel_event.touches[0].id = id;
+        cancel_event.touches[0].state = WebKit::WebTouchPoint::StateCancelled;
+        host_->skip_next_acked_touch_cancel() = true;

[sadrul, 2013/05/30 02:44:16]

ew no

[Yufeng Shen (Slow to review), 2013/05/30 22:34:38]

Done.

+        host_->ForwardTouchEvent(cancel_event);
+      }
+    }
+
+    if (event->type() == ui::ET_GESTURE_SCROLL_END ||
+        event->type() == ui::ET_SCROLL_FLING_START) {
+      host_->scroll_update_in_progress() = false;

[sadrul, 2013/05/30 02:44:16]

stahp

[Yufeng Shen (Slow to review), 2013/05/30 22:34:38]

Done.

+    }
+  }

[sadrul, 2013/05/30 02:44:16]

There may be a few more touch-move events in the touch-event queue when
scrolling starts. So it is necessary to flush all those events to the GR
immediately when this happens.

This is not a good place for doing this. It would be better to do this in
GestureEventFilter (although still a little awkward, perhaps), or near that part
of the code.

[Yufeng Shen (Slow to review), 2013/05/30 22:34:38]

moved to render_widge_host_impl.cc

+
   if (gesture.type != WebKit::WebInputEvent::Undefined) {
     host_->ForwardGestureEvent(gesture);