Keep browser process alive while there are platform apps with background pages running.

chrome/browser/extensions/api/media_galleries/media_galleries_apitest.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 "base/command_line.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
@@ skipping 114 matching lines @@
 
 IN_PROC_BROWSER_TEST_F(PlatformAppMediaGalleriesBrowserTest, NoGalleries) {
   EnsureMediaDirectoriesExists media_directories;
   ASSERT_TRUE(RunPlatformAppTest("api_test/media_galleries/no_galleries"))
       << message_;
 }
 
 IN_PROC_BROWSER_TEST_F(PlatformAppMediaGalleriesBrowserTest,
                        MediaGalleriesRead) {
   EnsureMediaDirectoriesExists media_directories;
-  ASSERT_TRUE(RunPlatformAppTest("api_test/media_galleries/read_access"))
-      << message_;
+  ASSERT_TRUE(RunPlatformAppTestReturnImmediately(
+      "api_test/media_galleries/read_access")) << message_;
   RunSecondTestPhase(media_directories.num_galleries());
+  CloseShellWindowsAndWaitForAppToExit();
 }
 
 IN_PROC_BROWSER_TEST_F(PlatformAppMediaGalleriesBrowserTest,
                        MediaGalleriesNoAccess) {
   EnsureMediaDirectoriesExists media_directories;
-  ASSERT_TRUE(RunPlatformAppTest("api_test/media_galleries/no_access"))
-      << message_;
+  ASSERT_TRUE(RunPlatformAppTestReturnImmediately(
+      "api_test/media_galleries/no_access")) << message_;
   RunSecondTestPhase(media_directories.num_galleries());
+  CloseShellWindowsAndWaitForAppToExit();
 }
 
 IN_PROC_BROWSER_TEST_F(ExperimentalMediaGalleriesApiTest,
                        ExperimentalMediaGalleries) {
   ASSERT_TRUE(RunExtensionTest("media_galleries/experimental")) << message_;
 }