mac: Prepare for -Wunused-functions.

content/browser/renderer_host/render_widget_host_view_guest.cc

Index: content/browser/renderer_host/render_widget_host_view_guest.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_guest.cc b/content/browser/renderer_host/render_widget_host_view_guest.cc
index 49c55fee85ebab69683e63be6393d233de9b49dd..dc174919452d0db5f8b044fdb0192b0a1fe32c91 100644
--- a/content/browser/renderer_host/render_widget_host_view_guest.cc
+++ b/content/browser/renderer_host/render_widget_host_view_guest.cc
@@ -29,6 +29,7 @@ namespace content {
 
 namespace {
 
+#if defined(OS_WIN) || defined(USE_AURA)
 bool ShouldSendPinchGesture() {
   static bool pinch_allowed =
       CommandLine::ForCurrentProcess()->HasSwitch(switches::kEnablePinch);
@@ -42,6 +43,7 @@ blink::WebGestureEvent CreateFlingCancelEvent(double time_stamp) {
   gesture_event.sourceDevice = blink::WebGestureEvent::Touchscreen;
   return gesture_event;
 }
+#endif  // defined(OS_WIN) || defined(USE_AURA)
 
 }  // namespace