Bug 910532 part 1 - Add flag to indicate prevent default from chrome. r=smaug

--HG--
extra : source : 0c9290ce08d739394df1787a05beff8dfddb1b4e

dom/events/Event.cpp

@@ -509,6 +509,8 @@ Event::PreventDefaultInternal(bool aCalledByDefaultHandler)
   // must be true when web apps check it after they call preventDefault().
   if (!aCalledByDefaultHandler) {
     mEvent->mFlags.mDefaultPreventedByContent = true;
+  } else {
+    mEvent->mFlags.mDefaultPreventedByChrome = true;
   }
 
   if (!IsTrusted()) {
@@ -569,6 +571,8 @@ Event::InitEvent(const nsAString& aEventTypeArg,
   mEvent->mFlags.mCancelable = aCancelableArg;
 
   mEvent->mFlags.mDefaultPrevented = false;
+  mEvent->mFlags.mDefaultPreventedByContent = false;
+  mEvent->mFlags.mDefaultPreventedByChrome = false;
 
   // Clearing the old targets, so that the event is targeted correctly when
   // re-dispatching it.

widget/BasicEvents.h

@@ -495,6 +495,10 @@ public:
   // consumed by content.
   // Note that mDefaultPrevented must be true when this is true.
   bool    mDefaultPreventedByContent : 1;
+  // If mDefaultPreventedByChrome is true, the event has been
+  // consumed by chrome.
+  // Note that mDefaultPrevented must be true when this is true.
+  bool    mDefaultPreventedByChrome : 1;
   // mMultipleActionsPrevented may be used when default handling don't want to
   // be prevented, but only one of the event targets should handle the event.
   // For example, when a <label> element is in another <label> element and