Implement mediaGalleriesPrivate api to notify extensions about gallery changed events.

chrome/browser/media_gallery/media_galleries_test_util.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/browser/media_gallery/media_galleries_test_util.h"
 
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/stringprintf.h"
@@ skipping 51 matching lines @@
   extension_service->EnableExtension(extension->id());
 
   return extension;
 }
 
 EnsureMediaDirectoriesExists::EnsureMediaDirectoriesExists()
     : num_galleries_(0) {
   Init();
 }
 
+bool EnsureMediaDirectoriesExists::AddNewFileInGallery(
+    int gallery_directory_key) {
+  if ((gallery_directory_key != chrome::DIR_USER_MUSIC) &&
+      (gallery_directory_key != chrome::DIR_USER_PICTURES) &&
+      (gallery_directory_key != chrome::DIR_USER_VIDEOS))
+    return false;
+
+  FilePath gallery_dir;
+  PathService::Get(gallery_directory_key, &gallery_dir);
+  FilePath gallery_file =
+    gallery_dir.Append(FILE_PATH_LITERAL("test1.txt"));
+  std::string content("new content");
+  int write_size = file_util::WriteFile(gallery_file, content.c_str(),
+                                        content.length());
+  return (write_size == static_cast<int>(content.length()));
+}
+
 void EnsureMediaDirectoriesExists::Init() {
 #if defined(OS_CHROMEOS) || defined(OS_ANDROID)
   return;
 #else
   ASSERT_TRUE(fake_dir_.CreateUniqueTempDir());
 
   const int kDirectoryKeys[] = {
     chrome::DIR_USER_MUSIC,
     chrome::DIR_USER_PICTURES,
     chrome::DIR_USER_VIDEOS,
@@ skipping 13 matching lines @@
     if (PathService::Get(kDirectoryKeys[i], &path) &&
         file_util::DirectoryExists(path)) {
       ++num_galleries_;
     }
   }
   ASSERT_GT(num_galleries_, 0);
 #endif
 }
 
 }  // namespace chrome