Move early return out of RootView::DispatchGestureEvent()

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/message_loop.h"
@@ skipping 237 matching lines @@
 ui::EventTarget* RootView::GetRootTarget() {
   return this;
 }
 
 ui::EventDispatchDetails RootView::OnEventFromSource(ui::Event* event) {
   // TODO(tdanderson): Replace the calls to Dispatch*Event() with calls to
   //                   EventProcessor::OnEventFromSource() once the code for
   //                   that event type has been refactored, and then
   //                   eventually remove this function altogether. See
   //                   crbug.com/348083.
-  if (event->IsKeyEvent())
+  if (event->IsKeyEvent()) {
     return EventProcessor::OnEventFromSource(event);
-  else if (event->IsScrollEvent())
+  } else if (event->IsScrollEvent()) {
     return EventProcessor::OnEventFromSource(event);
-  else if (event->IsTouchEvent())
+  } else if (event->IsTouchEvent()) {
     NOTREACHED() << "Touch events should not be sent to RootView.";
-  else if (event->IsGestureEvent())
+  } else if (event->IsGestureEvent()) {
+    // Ignore subsequent gesture scroll events if no handler was set for a
+    // ui::ET_GESTURE_SCROLL_BEGIN event.
+    if (!gesture_handler_ &&
+        (event->type() == ui::ET_GESTURE_SCROLL_UPDATE ||
+         event->type() == ui::ET_GESTURE_SCROLL_END ||
+         event->type() == ui::ET_SCROLL_FLING_START)) {
+      return DispatchDetails();
+    }
+
     DispatchGestureEvent(event->AsGestureEvent());
-  else if (event->IsMouseEvent())
+  } else if (event->IsMouseEvent()) {
     NOTREACHED() << "Should not be called with a MouseEvent.";
-  else
+  } else {
     NOTREACHED() << "Invalid event type.";
+  }

[sadrul, 2014/07/21 06:40:30]

Let's get rid of the elses in this block:
  if (key-event)
    return EventProcessor::OnEventFromSource(event);
  if (scroll-event)
    ..

[tdanderson, 2014/07/21 14:27:40]

Done.

 
   return DispatchDetails();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // RootView, View overrides:
 
 const Widget* RootView::GetWidget() const {
   return widget_;
 }
@@ skipping 395 matching lines @@
                    dispatch_details.target_destroyed) {
           return;
         }
       }
       scroll_gesture_handler_ = NULL;
     }
 
     return;
   }
 
-  // If there was no handler for a SCROLL_BEGIN event, then subsequent scroll
-  // events are not dispatched to any views.
-  switch (event->type()) {
-    case ui::ET_GESTURE_SCROLL_UPDATE:
-    case ui::ET_GESTURE_SCROLL_END:
-    case ui::ET_SCROLL_FLING_START:
-      return;
-    default:
-      break;
-  }
-
   View* gesture_handler = NULL;
   if (views::switches::IsRectBasedTargetingEnabled() &&
       !event->details().bounding_box().IsEmpty()) {
     // TODO(tdanderson): Pass in the bounding box to GetEventHandlerForRect()
     // once crbug.com/313392 is resolved.
     gfx::Rect touch_rect(event->details().bounding_box());
     touch_rect.set_origin(event->location());
     touch_rect.Offset(-touch_rect.width() / 2, -touch_rect.height() / 2);
     gesture_handler = GetEventHandlerForRect(touch_rect);
   } else {
@@ skipping 102 matching lines @@
 
 #ifndef NDEBUG
   DCHECK(!event_dispatch_target_ || Contains(event_dispatch_target_));
 #endif
 
   return details;
 }
 
 }  // namespace internal
 }  // namespace views