Bug 747873 - Provide error information on input device not properly configured. r=mwu

widget/gonk/nsAppShell.cpp

@@ -244,7 +244,11 @@ public:
 
     virtual void getReaderConfiguration(InputReaderConfiguration* outConfig);
     virtual sp<PointerControllerInterface> obtainPointerController(int32_t
-deviceId) { return NULL; };
+deviceId)
+    {
+        MOZ_NOT_REACHED("Input device configuration failed.");
+        return NULL;
+    };
     void setDisplayInfo();
 
 protected: