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

chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h

Index: chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h
diff --git a/chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h b/chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h
index 04b9054aaec04fb414ad7f6ba4b032e69e92040c..e282b05a45ae7c30fb2d899092db58dcc7fb1cbc 100644
--- a/chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h
+++ b/chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h
@@ -5,13 +5,16 @@
 #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;
@@ -30,8 +33,7 @@ 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();
@@ -54,6 +56,9 @@ struct EntryMetadata {
 // 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 };
 
@@ -63,6 +68,9 @@ class ProvidedFileSystemInterface {
     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;
 
@@ -79,6 +87,44 @@ class ProvidedFileSystemInterface {
   // 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
@@ -170,12 +216,35 @@ class ProvidedFileSystemInterface {
       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;
 };