[fsp] Add support for observing entries and notifying about changes.

chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h

 // Copyright 2014 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 CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_INTERFACE_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_INTERFACE_H_
 
+#include <map>
 #include <string>
+#include <vector>
 
 #include "base/callback.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "storage/browser/fileapi/async_file_util.h"
 
 class EventRouter;
 
 namespace base {
 class Time;
 }  // namespace base
 
 namespace net {
 class IOBuffer;
 }  // namespace net
 
 namespace chromeos {
 namespace file_system_provider {
 
 class ProvidedFileSystemInfo;
 class RequestManager;
 
-// Represents metadata for either a file or a directory. Returned by GetMetadata
-// method in ProvidedFileSystemInterface.
+// Represents metadata for either a file or a directory.
 struct EntryMetadata {
   EntryMetadata();
   ~EntryMetadata();
 
   bool is_directory;
   std::string name;
   int64 size;
   base::Time modification_time;
   std::string mime_type;
   std::string thumbnail;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(EntryMetadata);
 };
 
 // Interface for a provided file system. Acts as a proxy between providers
 // and clients. All of the request methods return an abort callback in order to
 // terminate it while running. They must be called on the same thread as the
 // request methods. The cancellation callback may be null if the operation
 // fails synchronously.
 class ProvidedFileSystemInterface {
  public:
+  struct ObservedEntry;
+  struct ChildChange;
+
   // Mode of opening a file. Used by OpenFile().
   enum OpenFileMode { OPEN_FILE_MODE_READ, OPEN_FILE_MODE_WRITE };
 
   // Extra fields to be fetched with metadata.
   enum MetadataField {
     METADATA_FIELD_DEFAULT = 0,
     METADATA_FIELD_THUMBNAIL = 1 << 0
   };
 
+  // Type of a change to an observed entry.
+  enum ChangeType { CHANGED, DELETED };
+
   typedef base::Callback<void(int file_handle, base::File::Error result)>
       OpenFileCallback;
 
   typedef base::Callback<
       void(int chunk_length, bool has_more, base::File::Error result)>
       ReadChunkReceivedCallback;
 
   typedef base::Callback<void(scoped_ptr<EntryMetadata> entry_metadata,
                               base::File::Error result)> GetMetadataCallback;
 
   typedef base::Callback<void(
       const storage::AsyncFileUtil::StatusCallback& callback)> AbortCallback;
 
   // Mask of fields requested from the GetMetadata() call.
   typedef int MetadataFieldMask;
 
+  // List of observed entries.
+  typedef std::map<base::FilePath, ObservedEntry> ObservedEntries;
+
+  // Lust of child changes.
+  typedef std::vector<ChildChange> ChildChanges;
+
+  // Represents an observed entry on the file system.
+  struct ObservedEntry {
+    ObservedEntry();
+    ~ObservedEntry();
+
+    base::FilePath entry_path;
+    bool recursive;
+    std::string last_tag;
+  };
+
+  // Describes a change in an entry contained in an observed directory.
+  struct ChildChange {
+    ChildChange();
+    ~ChildChange();
+
+    base::FilePath entry_path;
+    ChangeType change_type;
+  };
+
+  // Observer class to be notified about changes happened to the file system.
+  class Observer {
+   public:
+    // Called when an observed entry is changed, including removals.
+    virtual void OnEntryChanged(
+        const base::FilePath& observed_path,
+        ChangeType change_type,
+        const std::vector<ChildChange>& child_changes) = 0;
+
+    // Called when list of observed entries is changed.
+    virtual void OnObservedEntriesListChanged() = 0;
+  };
+
   virtual ~ProvidedFileSystemInterface() {}
 
   // Requests unmounting of the file system. The callback is called when the
   // request is accepted or rejected, with an error code.
   virtual AbortCallback RequestUnmount(
       const storage::AsyncFileUtil::StatusCallback& callback) = 0;
 
   // Requests metadata of the passed |entry_path|. It can be either a file
   // or a directory. All |fields| will be returned if supported. Note, that
   // default fields are always returned.
@@ skipping 71 matching lines @@
       const storage::AsyncFileUtil::StatusCallback& callback) = 0;
 
   // Requests writing to a file previously opened with |file_handle|.
   virtual AbortCallback WriteFile(
       int file_handle,
       net::IOBuffer* buffer,
       int64 offset,
       int length,
       const storage::AsyncFileUtil::StatusCallback& callback) = 0;
 
+  // Requests observing a directory.
+  virtual AbortCallback ObserveDirectory(
+      const base::FilePath& directory_path,
+      bool recursive,
+      const storage::AsyncFileUtil::StatusCallback& callback) = 0;
+
+  // Requests unobserving an entry.
+  virtual AbortCallback UnobserveEntry(
+      const base::FilePath& entry_path,
+      const storage::AsyncFileUtil::StatusCallback& callback) = 0;
+
   // Returns a provided file system info for this file system.
   virtual const ProvidedFileSystemInfo& GetFileSystemInfo() const = 0;
 
+  // Returns a mutable list of observed entries.
+  virtual ObservedEntries* GetObservedEntries() = 0;
+
   // Returns a request manager for the file system.
   virtual RequestManager* GetRequestManager() = 0;
 
+  // Adds an observer on the file system.
+  virtual void AddObserver(Observer* observer) = 0;
+
+  // Removes an observer.
+  virtual void RemoveObserver(Observer* observer) = 0;
+
+  // Gets a list of observers.
+  virtual ObserverList<Observer>* GetObservers() = 0;
+
   // Returns a weak pointer to this object.
   virtual base::WeakPtr<ProvidedFileSystemInterface> GetWeakPtr() = 0;
 };
 
 }  // namespace file_system_provider
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_INTERFACE_H_