Add support for refreshing contents of providers which don't support watchers.

chrome/browser/chromeos/file_system_provider/throttled_file_system_unittest.cc

 // Copyright 2015 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/chromeos/file_system_provider/throttled_file_system.h"
 
 #include <vector>
 
 #include "base/files/file.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 37 matching lines @@
   void SetUp() override {}
 
   // Initializes the throttled file system with |limit| number of opened files
   // at once. If 0, then no limit.
   void SetUpFileSystem(size_t limit) {
     MountOptions options(kFileSystemId, kDisplayName);
     options.opened_files_limit = limit;
 
     ProvidedFileSystemInfo file_system_info(
         kExtensionId, options, base::FilePath() /* mount_path */,
-        false /* configurable */, extensions::SOURCE_FILE);
+        false /* configurable */, true /* watchable */,
+        extensions::SOURCE_FILE);
 
     file_system_.reset(new ThrottledFileSystem(
         make_scoped_ptr(new FakeProvidedFileSystem(file_system_info))));
   }
 
   content::TestBrowserThreadBundle thread_bundle_;
   scoped_ptr<ThrottledFileSystem> file_system_;
 };
 
 TEST_F(FileSystemProviderThrottledFileSystemTest, OpenFile_LimitedToOneAtOnce) {
@@ skipping 81 matching lines @@
 
   base::RunLoop().RunUntilIdle();
 
   ASSERT_EQ(1u, first_open_log.size());
   EXPECT_EQ(base::File::FILE_OK, first_open_log[0].second);
   EXPECT_EQ(0u, second_open_log.size());
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos