Don't send touch events to windows like menus when the touch occurs outside the menu bounds.

ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
index 48368f962f2f3433b76c5ad20746ad28f135a481..58535cb389e31e7e6e8299477dc726e4766aedc9 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
@@ -85,7 +85,8 @@ DesktopWindowTreeHostWin::DesktopWindowTreeHostWin(
       should_animate_window_close_(false),
       pending_close_(false),
       has_non_client_view_(false),
-      tooltip_(NULL) {
+      tooltip_(NULL),
+      weak_factory_(this) {
 }
 
 DesktopWindowTreeHostWin::~DesktopWindowTreeHostWin() {
@@ -824,6 +825,23 @@ void DesktopWindowTreeHostWin::HandleTouchEvent(
     DesktopWindowTreeHostWin* target =
         host->window()->GetProperty(kDesktopWindowTreeHostKey);
     if (target && target->HasCapture() && target != this) {
+      // Windows like menus need to be closed if a touch occurs outside the
+      // bounds of the window.
+      if ((event.type() == ui::ET_TOUCH_PRESSED) &&
+          GetWidget()->GetNativeView()->GetProperty(
+              aura::client::kReleaseCaptureOnTouchOutside)) {
+        target->ReleaseCapture();
+        // We should send the touch to the correct window. We use PostTask here
+        // as we don't want to send the touch event in the context of the
+        // nested loop if any.
+        base::MessageLoop::current()->PostTask(

[sky, 2016/01/08 23:51:56]

Is there no way to have the menu code do the posting so that we don't need
kReleaseCaptureOnTouchOutside?

[ananta, 2016/01/09 00:01:15]

The touch events are handled by the gesture recognizer in the PredispatchEvent
phase. It short circuits them there and ensures that we will only see gestures
in chrome.

The code is here
https://code.google.com/p/chromium/codesearch#chromium/src/ui/aura/window_eve...
and that basically forwards the event to the gesture recognizer which short
circuits it

+            FROM_HERE,
+            base::Bind(&DesktopWindowTreeHostWin::PostEventToProcessor,
+                       weak_factory_.GetWeakPtr(),
+                       event));
+        return;
+      }
+
       POINT target_location(event.location().ToPOINT());
       ClientToScreen(GetHWND(), &target_location);
       ScreenToClient(target->GetHWND(), &target_location);
@@ -949,6 +967,11 @@ bool DesktopWindowTreeHostWin::IsModalWindowActive() const {
   return false;
 }
 
+void DesktopWindowTreeHostWin::PostEventToProcessor(
+    const ui::Event& event) {
+  SendEventToProcessor(const_cast<ui::Event*>(&event));
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopWindowTreeHost, public: