mediaview: Mount ARC documents provider file system volumes.

components/arc/file_system/arc_file_system_observer.h

Index: components/arc/file_system/arc_file_system_observer.h
diff --git a/components/arc/file_system/arc_file_system_observer.h b/components/arc/file_system/arc_file_system_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..a8b6c431dacd67a69c74ff31b92f5d0e9b9b1ae0
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+++ b/components/arc/file_system/arc_file_system_observer.h
@@ -0,0 +1,19 @@
+// Copyright 2017 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.
+
+#ifndef COMPONENTS_ARC_FILE_SYSTEM_ARC_FILE_SYSTEM_OBSERVER_H_
+#define COMPONENTS_ARC_FILE_SYSTEM_ARC_FILE_SYSTEM_OBSERVER_H_
+
+namespace arc {
+
+class ArcFileSystemObserver {
+ public:
+  virtual ~ArcFileSystemObserver() = default;
+  // Called when ARC file systems are ready.
+  virtual void OnFileSystemsReady() = 0;
+};
+
+}  // namespace arc
+
+#endif  // COMPONENTS_ARC_FILE_SYSTEM_ARC_FILE_SYSTEM_OBSERVER_H_