Enumerate the return value of dispatchEvent so it is clear.

third_party/WebKit/Source/core/events/MouseEvent.cpp

Index: third_party/WebKit/Source/core/events/MouseEvent.cpp
diff --git a/third_party/WebKit/Source/core/events/MouseEvent.cpp b/third_party/WebKit/Source/core/events/MouseEvent.cpp
index 9b8d3e1aedffc63db881c837e0fbcaa824911947..129e63d93cd2108636c269b4427a031b436974a9 100644
--- a/third_party/WebKit/Source/core/events/MouseEvent.cpp
+++ b/third_party/WebKit/Source/core/events/MouseEvent.cpp
@@ -266,7 +266,7 @@ MouseEvent& MouseEventDispatchMediator::event() const
     return toMouseEvent(EventDispatchMediator::event());
 }
 
-bool MouseEventDispatchMediator::dispatchEvent(EventDispatcher& dispatcher) const
+EventTarget::DispatchEventResult MouseEventDispatchMediator::dispatchEvent(EventDispatcher& dispatcher) const
 {
     MouseEvent& mouseEvent = event();
     if (!mouseEvent.isTrusted()) {
@@ -275,21 +275,20 @@ bool MouseEventDispatchMediator::dispatchEvent(EventDispatcher& dispatcher) cons
     }
 
     if (isDisabledFormControl(&dispatcher.node()))
-        return false;
+        return EventTarget::DispatchEventResult::HandledSuppressed;
 
     if (mouseEvent.type().isEmpty())
-        return true; // Shouldn't happen.
+        return EventTarget::DispatchEventResult::NotHandled; // Shouldn't happen.
 
     ASSERT(!mouseEvent.target() || mouseEvent.target() != mouseEvent.relatedTarget());
 
     EventTarget* relatedTarget = mouseEvent.relatedTarget();
     mouseEvent.eventPath().adjustForRelatedTarget(dispatcher.node(), relatedTarget);
 
-    dispatcher.dispatch();
-    bool swallowEvent = mouseEvent.defaultHandled() || mouseEvent.defaultPrevented();
+    EventTarget::DispatchEventResult result = dispatcher.dispatch();
 
     if (mouseEvent.type() != EventTypeNames::click || mouseEvent.detail() != 2)
-        return !swallowEvent;
+        return result;
 
     // Special case: If it's a double click event, we also send the dblclick event. This is not part
     // of the DOM specs, but is used for compatibility with the ondblclick="" attribute. This is treated
@@ -303,10 +302,10 @@ bool MouseEventDispatchMediator::dispatchEvent(EventDispatcher& dispatcher) cons
     doubleClickEvent->setTrusted(mouseEvent.isTrusted());
     if (mouseEvent.defaultHandled())
         doubleClickEvent->setDefaultHandled();
-    EventDispatcher::dispatchEvent(dispatcher.node(), MouseEventDispatchMediator::create(doubleClickEvent));
-    if (doubleClickEvent->defaultHandled() || doubleClickEvent->defaultPrevented())
-        return false;
-    return !swallowEvent;
+    EventTarget::DispatchEventResult doubleClickEventResult = EventDispatcher::dispatchEvent(dispatcher.node(), MouseEventDispatchMediator::create(doubleClickEvent));
+    if (result != EventTarget::DispatchEventResult::NotHandled)

[tkent, 2016/02/22 01:40:22]

The logic looks different from the original code.

Original code:
  If |doubleClickEvent| was handled, returns false. Otherwise, returns the
result of |mouseEvent|.
This CL:
  If |mouseEvent| was handled, returns the result of |mouseEvent|.  Otherwise,
returns the result of |doubleClickEvent|.

[dtapuska, 2016/02/23 19:14:40]

Done.

+        return result;
+    return doubleClickEventResult;
 }
 
 } // namespace blink