mediaview: Mount ARC documents provider file system volumes.

chrome/browser/chromeos/arc/fileapi/arc_file_system_service.h

Index: chrome/browser/chromeos/arc/fileapi/arc_file_system_service.h
diff --git a/chrome/browser/chromeos/arc/fileapi/arc_file_system_service.h b/chrome/browser/chromeos/arc/fileapi/arc_file_system_service.h
index 11be0cefc4a37aa7e8cd523b56ae8276b8e9a316..90800047bcd4e83d5e16969cf19dcce8fd1422e7 100644
--- a/chrome/browser/chromeos/arc/fileapi/arc_file_system_service.h
+++ b/chrome/browser/chromeos/arc/fileapi/arc_file_system_service.h
@@ -6,19 +6,37 @@
 #define CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_FILE_SYSTEM_SERVICE_H_
 
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "components/arc/arc_service.h"
+#include "components/arc/common/file_system.mojom.h"
+#include "components/arc/instance_holder.h"
 
 namespace arc {
 
 class ArcBridgeService;
+class ArcFileSystemObserver;
 
 // ArcFileSystemService registers ARC file systems to the system.
-class ArcFileSystemService : public ArcService {
+class ArcFileSystemService
+    : public ArcService,
+      public InstanceHolder<mojom::FileSystemInstance>::Observer {
  public:
   explicit ArcFileSystemService(ArcBridgeService* bridge_service);
   ~ArcFileSystemService() override;
 
+  void AddObserver(ArcFileSystemObserver* observer);
+  void RemoveObserver(ArcFileSystemObserver* observer);
+
+  // InstanceHolder<mojom::FileSystemInstance>::Observer overrides:
+  void OnInstanceReady() override;
+  void OnInstanceClosed() override;
+
+  // For supporting ArcServiceManager::GetService<T>().
+  static const char kArcServiceName[];
+
  private:
+  base::ObserverList<ArcFileSystemObserver> observer_list_;
+
   DISALLOW_COPY_AND_ASSIGN(ArcFileSystemService);
 };