Make sure only the right processes can access the profile path.

chrome/app/chrome_main_delegate.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 "chrome/app/chrome_main_delegate.h"
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop.h"
 #include "base/metrics/field_trial.h"
@@ skipping 553 matching lines @@
 
   InitMacCrashReporter(command_line, process_type);
 #endif
 
   // Notice a user data directory override if any
   FilePath user_data_dir =
       command_line.GetSwitchValuePath(switches::kUserDataDir);
 #if defined(OS_MACOSX) || defined(OS_WIN)
   CheckUserDataDirPolicy(&user_data_dir);
 #endif
-  if (!user_data_dir.empty())
-    CHECK(PathService::Override(chrome::DIR_USER_DATA, user_data_dir));
+  if (!user_data_dir.empty()) {
+    CHECK(PathService::Override(chrome::DIR_USER_DATA, user_data_dir,
+                                chrome::ProcessNeedsProfileDir(process_type)));
+  }
 
   startup_timer_.reset(new base::StatsScope<base::StatsCounterTimer>
                        (content::Counters::chrome_main()));
 
   // Enable the heap profiler as early as possible!
   EnableHeapProfiler(command_line);
 
   // Enable Message Loop related state asap.
   if (command_line.HasSwitch(switches::kMessageLoopHistogrammer))
     MessageLoop::EnableHistogrammer(true);
@@ skipping 170 matching lines @@
 
 #if defined(USE_LINUX_BREAKPAD)
   // Needs to be called after we have chrome::DIR_USER_DATA.  BrowserMain sets
   // this up for the browser process in a different manner.
   InitCrashReporter();
 #endif
 
   InitializeChromeContentClient(process_type);
 }
 #endif  // OS_MACOSX