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

 // 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.
 
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host_win.h"
 
 #include "base/win/metro.h"
 #include "third_party/skia/include/core/SkPath.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "ui/aura/client/aura_constants.h"
@@ skipping 67 matching lines @@
     internal::NativeWidgetDelegate* native_widget_delegate,
     DesktopNativeWidgetAura* desktop_native_widget_aura)
     : message_handler_(new HWNDMessageHandler(this)),
       native_widget_delegate_(native_widget_delegate),
       desktop_native_widget_aura_(desktop_native_widget_aura),
       content_window_(NULL),
       drag_drop_client_(NULL),
       should_animate_window_close_(false),
       pending_close_(false),
       has_non_client_view_(false),
-      tooltip_(NULL) {
+      tooltip_(NULL),
+      weak_factory_(this) {
 }
 
 DesktopWindowTreeHostWin::~DesktopWindowTreeHostWin() {
   // WARNING: |content_window_| has been destroyed by the time we get here.
   desktop_native_widget_aura_->OnDesktopWindowTreeHostDestroyed(this);
   DestroyDispatcher();
 }
 
 // static
 aura::Window* DesktopWindowTreeHostWin::GetContentWindowForHWND(HWND hwnd) {
@@ skipping 718 matching lines @@
   if (!GetWidget()->GetNativeView())
     return;
 
   // Currently we assume the window that has capture gets touch events too.
   aura::WindowTreeHost* host =
       aura::WindowTreeHost::GetForAcceleratedWidget(GetCapture());
   if (host) {
     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);
       ui::TouchEvent target_event(event, static_cast<View*>(NULL),
                                   static_cast<View*>(NULL));
       target_event.set_location(gfx::Point(target_location));
       target_event.set_root_location(target_event.location());
       target->SendEventToProcessor(&target_event);
       return;
     }
@@ skipping 105 matching lines @@
   for (index = window()->children().begin();
        index != window()->children().end();
        ++index) {
     if ((*index)->GetProperty(aura::client::kModalKey) !=
         ui:: MODAL_TYPE_NONE && (*index)->TargetVisibility())
       return true;
   }
   return false;
 }
 
+void DesktopWindowTreeHostWin::PostEventToProcessor(
+    const ui::Event& event) {
+  SendEventToProcessor(const_cast<ui::Event*>(&event));
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopWindowTreeHost, public:
 
 // static
 DesktopWindowTreeHost* DesktopWindowTreeHost::Create(
     internal::NativeWidgetDelegate* native_widget_delegate,
     DesktopNativeWidgetAura* desktop_native_widget_aura) {
   return new DesktopWindowTreeHostWin(native_widget_delegate,
                                       desktop_native_widget_aura);
 }
 
 }  // namespace views