Cleanup: Remove unused variables in chrome/ found by Scythe.

chrome/browser/ui/zoom/zoom_controller_browsertest.cc

Index: chrome/browser/ui/zoom/zoom_controller_browsertest.cc
diff --git a/chrome/browser/ui/zoom/zoom_controller_browsertest.cc b/chrome/browser/ui/zoom/zoom_controller_browsertest.cc
index bf863e827e554921a335fa9511f7fa016e6da2ed..d8bcbddfabd687c2b0024ad45199c81e0b2fdd7d 100644
--- a/chrome/browser/ui/zoom/zoom_controller_browsertest.cc
+++ b/chrome/browser/ui/zoom/zoom_controller_browsertest.cc
@@ -42,8 +42,7 @@ class ZoomChangedWatcher : public ZoomObserver {
   ZoomChangedWatcher(
       content::WebContents* web_contents,
       const ZoomController::ZoomChangedEventData& expected_event_data)
-      : web_contents_(web_contents),
-        expected_event_data_(expected_event_data),
+      : expected_event_data_(expected_event_data),
         message_loop_runner_(new content::MessageLoopRunner) {
     ZoomController::FromWebContents(web_contents)->AddObserver(this);
   }
@@ -58,7 +57,6 @@ class ZoomChangedWatcher : public ZoomObserver {
   }
 
  private:
-  content::WebContents* web_contents_;
   ZoomController::ZoomChangedEventData expected_event_data_;
   scoped_refptr<content::MessageLoopRunner> message_loop_runner_;