views: Target the synthetic wheel events to the view under the mouse cursor.

ui/views/widget/root_view.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/root_view.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 121 matching lines @@
 
   if (consumed)
     event->StopPropagation();
 }
 
 void RootView::DispatchScrollEvent(ui::ScrollEvent* event) {
   for (View* v = GetEventHandlerForPoint(event->location());
        v && v != this && !event->stopped_propagation(); v = v->parent()) {
     v->OnScrollEvent(event);
   }
+
+  if (event->handled() || event->type() != ui::ET_SCROLL)
+    return;
+
+  // Convert unprocessed scroll events into mouse-wheel events. Note that
+  // wheel events are normally sent to the focused view. However, if the focused
+  // view does not process these wheel events, then dispatch them to the view
+  // under the cursor.
+  ui::MouseWheelEvent wheel(*event);
+  if (OnMouseWheel(wheel)) {
+    event->SetHandled();
+  } else {
+    View* focused_view =
+        GetFocusManager() ? GetFocusManager()->GetFocusedView() : NULL;
+    View* v = GetEventHandlerForPoint(wheel.location());
+    if (v != focused_view) {
+      for (; v && v != this; v = v->parent()) {
+        if (v->OnMouseWheel(wheel)) {
+          event->SetHandled();
+          break;
+        }
+      }
+    }
+  }
 }
 
 void RootView::DispatchTouchEvent(ui::TouchEvent* event) {
   // TODO: this looks all wrong. On a TOUCH_PRESSED we should figure out the
   // view and target that view with all touches with the same id until the
   // release (or keep it if captured).
 
   // If touch_pressed_handler_ is non null, we are currently processing
   // a touch down on the screen situation. In that case we send the
   // event to touch_pressed_handler_
@@ skipping 475 matching lines @@
 }
 
 void RootView::SetMouseLocationAndFlags(const ui::MouseEvent& event) {
   last_mouse_event_flags_ = event.flags();
   last_mouse_event_x_ = event.x();
   last_mouse_event_y_ = event.y();
 }
 
 }  // namespace internal
 }  // namespace views