[Mac] Make profile-locking error the same as failing to lock.

chrome/browser/process_singleton_mac.cc

 // Copyright (c) 2009 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 <errno.h>
 #include <fcntl.h>
 #include <sys/file.h>
 
 #include "chrome/browser/process_singleton.h"
 
@@ skipping 44 matching lines @@
   // This space intentionally left blank.
   return PROCESS_NONE;
 }
 
 ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcessOrCreate() {
   // Windows tries NotifyOtherProcess() first.
   return Create() ? PROCESS_NONE : PROFILE_IN_USE;
 }
 
 // Attempt to acquire an exclusive lock on an empty file in the
-// profile directory.  Returns |true| if it gets the lock.
-// TODO(shess): The older code always returned |true|.  Monitor the
-// histograms and convert the marked failure cases to |false| once
-// it's clear that it is safe to do.  http://crbug.com/58986
+// profile directory.  Returns |true| if it gets the lock.  Returns
+// |false| if the lock is held, or if there is an error.
 // TODO(shess): Rather than logging failures, popup an alert.  Punting
 // that for now because it would require confidence that this code is
 // never called in a situation where an alert wouldn't work.
 // http://crbug.com/59061
 bool ProcessSingleton::Create() {
   DCHECK_EQ(-1, lock_fd_) << "lock_path_ is already open.";
 
   lock_fd_ = HANDLE_EINTR(open(lock_path_.value().c_str(),
                                O_RDONLY | O_CREAT, 0644));
   if (lock_fd_ == -1) {
     const int capture_errno = errno;
     DPCHECK(lock_fd_ != -1) << "Unexpected failure opening profile lockfile";
     UMA_HISTOGRAM_ENUMERATION("ProcessSingleton.OpenError",
                               capture_errno, kMaxErrno);
-    // TODO(shess): Change to |false|.
-    return true;
+    return false;
   }
 
   // Acquire an exclusive lock in non-blocking fashion.  If the lock
   // is already held, this will return |EWOULDBLOCK|.
   int rc = HANDLE_EINTR(flock(lock_fd_, LOCK_EX|LOCK_NB));
   if (rc == -1) {
     const int capture_errno = errno;
     DPCHECK(errno == EWOULDBLOCK)
         << "Unexpected failure locking profile lockfile";
 
     Cleanup();
 
     // Other errors indicate something crazy is happening.
     if (capture_errno != EWOULDBLOCK) {
       UMA_HISTOGRAM_ENUMERATION("ProcessSingleton.LockError",
                                 capture_errno, kMaxErrno);
-      // TODO(shess): Change to |false|.
-      return true;
+      return false;
     }
 
     // The file is open by another process and locked.
     LOG(ERROR) << "Unable to obtain profile lock.";
     return false;
   }
 
   return true;
 }
 
 void ProcessSingleton::Cleanup() {
   // Closing the file also releases the lock.
   if (lock_fd_ != -1) {
     int rc = HANDLE_EINTR(close(lock_fd_));
     DPCHECK(!rc) << "Closing lock_fd_:";
   }
   lock_fd_ = -1;
 }