Bug 1112212 - Add may-have flags for key event and input event listeners; r=smaug

dom/events/EventListenerManager.cpp

@@ -101,6 +101,8 @@ EventListenerManager::EventListenerManager(EventTarget* aTarget)
   , mMayHaveTouchEventListener(false)
   , mMayHaveMouseEnterLeaveEventListener(false)
   , mMayHavePointerEnterLeaveEventListener(false)
+  , mMayHaveKeyEventListener(false)
+  , mMayHaveInputOrCompositionEventListener(false)
   , mClearingListeners(false)
   , mIsMainThreadELM(NS_IsMainThread())
   , mNoListenerForEvent(0)
@@ -376,7 +378,21 @@ EventListenerManager::AddEventListenerInternal(
       window->SetHasGamepadEventListener();
     }
 #endif
+  } else if (aTypeAtom == nsGkAtoms::onkeydown ||
+             aTypeAtom == nsGkAtoms::onkeypress ||
+             aTypeAtom == nsGkAtoms::onkeyup) {
+    if (!aFlags.mInSystemGroup) {
+      mMayHaveKeyEventListener = true;
+    }
+  } else if (aTypeAtom == nsGkAtoms::oncompositionend ||
+             aTypeAtom == nsGkAtoms::oncompositionstart ||
+             aTypeAtom == nsGkAtoms::oncompositionupdate ||
+             aTypeAtom == nsGkAtoms::oninput) {
+    if (!aFlags.mInSystemGroup) {
+      mMayHaveInputOrCompositionEventListener = true;
+    }
   }
+
   if (aTypeAtom && mTarget) {
     mTarget->EventListenerAdded(aTypeAtom);
   }

dom/events/EventListenerManager.h

@@ -397,6 +397,19 @@ public:
   bool MayHaveMouseEnterLeaveEventListener() { return mMayHaveMouseEnterLeaveEventListener; }
   bool MayHavePointerEnterLeaveEventListener() { return mMayHavePointerEnterLeaveEventListener; }
 
+  /**
+   * Returns true if there may be a key event listener (keydown, keypress,
+   * or keyup) registered, or false if there definitely isn't.
+   */
+  bool MayHaveKeyEventListener() { return mMayHaveKeyEventListener; }
+
+  /**
+   * Returns true if there may be an advanced input event listener (input,
+   * compositionstart, compositionupdate, or compositionend) registered,
+   * or false if there definitely isn't.
+   */
+  bool MayHaveInputOrCompositionEventListener() { return mMayHaveInputOrCompositionEventListener; }
+
   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const;
 
   uint32_t ListenerCount() const
@@ -546,9 +559,11 @@ protected:
   uint32_t mMayHaveTouchEventListener : 1;
   uint32_t mMayHaveMouseEnterLeaveEventListener : 1;
   uint32_t mMayHavePointerEnterLeaveEventListener : 1;
+  uint32_t mMayHaveKeyEventListener : 1;
+  uint32_t mMayHaveInputOrCompositionEventListener : 1;
   uint32_t mClearingListeners : 1;
   uint32_t mIsMainThreadELM : 1;
-  uint32_t mNoListenerForEvent : 23;
+  uint32_t mNoListenerForEvent : 21;
 
   nsAutoTObserverArray<Listener, 2> mListeners;
   dom::EventTarget* MOZ_NON_OWNING_REF mTarget;