Store the NSEvent.description in a crash key in -[BrowserCrApplication sendEvent:].

chrome/browser/chrome_browser_application_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/chrome_browser_application_mac.h"
 
 #include <AvailabilityMacros.h>
 #include <objc/objc-exception.h>
 
 #import "base/auto_reset.h"
@@ skipping 333 matching lines @@
 
 - (BOOL)isHandlingSendEvent {
   return handlingSendEvent_;
 }
 
 - (void)setHandlingSendEvent:(BOOL)handlingSendEvent {
   handlingSendEvent_ = handlingSendEvent;
 }
 
 - (void)sendEvent:(NSEvent*)event {
+  base::debug::ScopedCrashKey crash_key(
+      crash_keys::mac::kNSEvent, base::SysNSStringToUTF8([event description]));
+
   base::mac::CallWithEHFrame(^{
     switch (event.type) {
       case NSLeftMouseDown:
       case NSRightMouseDown: {
         // In kiosk mode, we want to prevent context menus from appearing,
         // so simply discard menu-generating events instead of passing them
         // along.
         bool kioskMode = base::CommandLine::ForCurrentProcess()->HasSwitch(
             switches::kKioskMode);
         bool ctrlDown = [event modifierFlags] & NSControlKeyMask;
@@ skipping 25 matching lines @@
 - (void)_cycleWindowsReversed:(BOOL)arg1 {
   base::AutoReset<BOOL> pin(&cyclingWindows_, YES);
   [super _cycleWindowsReversed:arg1];
 }
 
 - (BOOL)isCyclingWindows {
   return cyclingWindows_;
 }
 
 @end