Always call StorageMonitor::RemoveObserver in ~MediaFileSystemRegistry.

chrome/browser/media_galleries/media_file_system_registry_unittest.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.
 
 // MediaFileSystemRegistry unit tests.
 
 #include "chrome/browser/media_galleries/media_file_system_registry.h"
 
 #include <stddef.h>
 
@@ skipping 772 matching lines @@
   ASSERT_TRUE(base::CreateDirectory(dcim_dir_));
   ASSERT_TRUE(base::CreateDirectory(
       dcim_dir_.Append(storage_monitor::kDCIMDirectoryName)));
 }
 
 void MediaFileSystemRegistryTest::TearDown() {
   profile_states_.clear();
   MediaFileSystemRegistry* registry =
       g_browser_process->media_file_system_registry();
   EXPECT_EQ(0U, GetExtensionGalleriesHostCount(registry));
-  TestStorageMonitor::Destroy();
+
 #if defined(OS_CHROMEOS)
   test_user_manager_.reset();
 #endif
 
+  // The TestingProfile must be destroyed before the TestingBrowserProcess
+  // because it uses it in its destructor.
   ChromeRenderViewHostTestHarness::TearDown();
+
+  // The MediaFileSystemRegistry owned by the TestingBrowserProcess must be
+  // destroyed before the StorageMonitor because it calls
+  // StorageMonitor::RemoveObserver() in its destructor.
+  TestingBrowserProcess::DeleteInstance();
+
+  TestStorageMonitor::Destroy();
 }
 
 ///////////
 // Tests //
 ///////////
 
 TEST_F(MediaFileSystemRegistryTest, Basic) {
   CreateProfileState(1);
   AssertAllAutoAddedGalleries();
 
@@ skipping 262 matching lines @@
       fs_info.begin()->second.fsid).empty());
 
   // Revoke permission and ensure that the file system is revoked.
   SetGalleryPermission(profile_state,
                        profile_state->regular_permission_extension(),
                        device_id,
                        false /*has access*/);
   EXPECT_TRUE(test_file_system_context()->GetRegisteredPath(
       fs_info.begin()->second.fsid).empty());
 }