Only set MouseLockDispatcher unlocked_by_target_ after mouse lock confirmed.

content/renderer/mouse_lock_dispatcher.cc

 // 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.
 
 #include "content/renderer/mouse_lock_dispatcher.h"
 
 #include "base/logging.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebInputEvent.h"
 
 MouseLockDispatcher::MouseLockDispatcher() : mouse_locked_(false),
@@ skipping 14 matching lines @@
   target_ = target;
 
   SendLockMouseRequest(unlocked_by_target_);
   unlocked_by_target_ = false;
   return true;
 }
 
 void MouseLockDispatcher::UnlockMouse(LockTarget* target) {
   if (target && target == target_ && !pending_unlock_request_) {
     pending_unlock_request_ = true;
-    unlocked_by_target_ = true;
+
+    // When a target application voluntarily unlocks the mouse we permit
+    // relocking the mouse silently and with no user gesture requirement.
+    // Check that the lock request is not currently pending and not yet
+    // accepted by the browser process before setting |unlocked_by_target_|.
+    if (!pending_lock_request_)
+      unlocked_by_target_ = true;
+
     SendUnlockMouseRequest();
   }
 }
 
 void MouseLockDispatcher::OnLockTargetDestroyed(LockTarget* target) {
   if (target == target_) {
     UnlockMouse(target);
     target_ = NULL;
   }
 }
@@ skipping 40 matching lines @@
 
   LockTarget* last_target = target_;
   target_ = NULL;
 
   // Callbacks made after all state modification to prevent reentrant errors
   // such as OnMouseLockLost() synchronously calling LockMouse().
 
   if (last_target)
     last_target->OnMouseLockLost();
 }