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

chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h

Index: chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h
diff --git a/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h b/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h
index f9dd955fa9e6b3aafefbd450a6ca0136ea218395..28a5f6b06742b7e1d49cd8cf455f687ab6d5e55e 100644
--- a/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h
+++ b/chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h
@@ -12,9 +12,11 @@
 #include "base/callback.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "chrome/browser/chromeos/file_system_provider/provided_file_system_info.h"
 #include "chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h"
+#include "chrome/browser/chromeos/file_system_provider/provided_file_system_observer.h"
 
 class Profile;
 
@@ -122,8 +124,23 @@ class FakeProvidedFileSystem : public ProvidedFileSystemInterface {
       int64 offset,
       int length,
       const storage::AsyncFileUtil::StatusCallback& callback) OVERRIDE;
+  virtual AbortCallback ObserveDirectory(

[mtomasz, 2014/10/03 04:22:47]

Currently we support observing directories only, never single files, but it will
be added as ObserveFile in the future.

I want to separate these two methods, since |recursive| doesn't make sense for
files, but only for directories.

+      const base::FilePath& directory_path,
+      bool recursive,
+      const storage::AsyncFileUtil::StatusCallback& callback) OVERRIDE;
+  virtual AbortCallback UnobserveEntry(

[mtomasz, 2014/10/03 04:22:47]

Method for unobserving files would have the same signature, hence there will be
only one method UnobserveEntry which will unobserve both directories and files.

+      const base::FilePath& entry_path,
+      const storage::AsyncFileUtil::StatusCallback& callback) OVERRIDE;
   virtual const ProvidedFileSystemInfo& GetFileSystemInfo() const OVERRIDE;
   virtual RequestManager* GetRequestManager() OVERRIDE;
+  virtual ObservedEntries* GetObservedEntries() OVERRIDE;
+  virtual void AddObserver(ProvidedFileSystemObserver* observer) OVERRIDE;

[mtomasz, 2014/10/03 04:22:47]

Cache implementation will add itself as an observer. So it will be able to
invalidate entries which are changed remotely.

+  virtual void RemoveObserver(ProvidedFileSystemObserver* observer) OVERRIDE;
+  virtual bool Notify(

[mtomasz, 2014/10/03 04:22:47]

This is called from file_system_provider_api.cc, so by providing extensions.
This method simply updates the tag in the internal collection of observed
entries, and notifies observers.

+      const base::FilePath& observed_path,
+      ProvidedFileSystemObserver::ChangeType change_type,
+      const ProvidedFileSystemObserver::ChildChanges& child_changes,
+      const std::string& tag) OVERRIDE;
   virtual base::WeakPtr<ProvidedFileSystemInterface> GetWeakPtr() OVERRIDE;
 
   // Factory callback, to be used in Service::SetFileSystemFactory(). The
@@ -156,6 +173,7 @@ class FakeProvidedFileSystem : public ProvidedFileSystemInterface {
   OpenedFilesMap opened_files_;
   int last_file_handle_;
   base::CancelableTaskTracker tracker_;
+  ObserverList<ProvidedFileSystemObserver> observers_;
 
   base::WeakPtrFactory<FakeProvidedFileSystem> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(FakeProvidedFileSystem);