Bug 982118 - Move ui.click_hold_context_menus.delay to gfxPrefs. r=kgupta

gfx/layers/ipc/GestureEventListener.cpp

@@ -85,7 +85,7 @@ nsEventStatus GestureEventListener::HandleInputEvent(const MultiTouchInput& aEve
 
         mAsyncPanZoomController->PostDelayedTask(
           mLongTapTimeoutTask,
-          Preferences::GetInt("ui.click_hold_context_menus.delay", 500));
+          gfxPrefs::UiClickHoldContextMenusDelay());
       }
     } else if (length == 2) {
       // Another finger has been added; it can't be a tap anymore.

gfx/thebes/gfxPrefs.h

@@ -176,6 +176,7 @@ private:
   DECL_GFX_PREF(Once, "layout.frame_rate",                     LayoutFrameRate, int32_t, -1);
 
   DECL_GFX_PREF(Live, "nglayout.debug.widget_update_flashing", WidgetUpdateFlashing, bool, false);
+  DECL_GFX_PREF(Live, "ui.click_hold_context_menus.delay",     UiClickHoldContextMenusDelay, int32_t, 500);
 
   DECL_GFX_PREF(Once, "webgl.force-layers-readback",           WebGLForceLayersReadback, bool, false);