[fsp] Let extensions decide about the file system id.

chrome/browser/chromeos/file_system_provider/service.h

Index: chrome/browser/chromeos/file_system_provider/service.h
diff --git a/chrome/browser/chromeos/file_system_provider/service.h b/chrome/browser/chromeos/file_system_provider/service.h
index f5554bd4592fa0e5bff94e5fdce8f3b4aac1587c..d98276792617c458e134684df3c85fbab91a5229 100644
--- a/chrome/browser/chromeos/file_system_provider/service.h
+++ b/chrome/browser/chromeos/file_system_provider/service.h
@@ -7,6 +7,7 @@
 
 #include <map>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "base/files/file.h"
@@ -55,19 +56,21 @@ class Service : public KeyedService,
       const FileSystemFactoryCallback& factory_callback);
 
   // Mounts a file system provided by an extension with the |extension_id|.
-  // For success, it returns a numeric file system id, which is an
-  // auto-incremented non-zero value. For failures, it returns zero.
-  int MountFileSystem(const std::string& extension_id,
-                      const std::string& file_system_name);
+  // For success, returns true, otherwise false.
+  bool MountFileSystem(const std::string& extension_id,
+                       const std::string& file_system_id,
+                       const std::string& file_system_name);
 
   // Unmounts a file system with the specified |file_system_id| for the
   // |extension_id|. For success returns true, otherwise false.
-  bool UnmountFileSystem(const std::string& extension_id, int file_system_id);
+  bool UnmountFileSystem(const std::string& extension_id,
+                         const std::string& file_system_id);
 
   // Requests unmounting of the file system. The callback is called when the
   // request is accepted or rejected, with an error code. Returns false if the
   // request could not been created, true otherwise.
-  bool RequestUnmount(int file_system_id);
+  bool RequestUnmount(const std::string& extension_id,
+                      const std::string& file_system_id);
 
   // Returns a list of information of all currently provided file systems. All
   // items are copied.
@@ -77,7 +80,7 @@ class Service : public KeyedService,
   // the extension with |extension_id|. If not found, then returns NULL.
   ProvidedFileSystemInterface* GetProvidedFileSystem(
       const std::string& extension_id,
-      int file_system_id);
+      const std::string& file_system_id);
 
   // Returns a provided file system attached to the the passed
   // |mount_point_name|. If not found, then returns NULL.
@@ -98,8 +101,13 @@ class Service : public KeyedService,
       extensions::UnloadedExtensionInfo::Reason reason) OVERRIDE;
 
  private:
-  typedef std::map<int, ProvidedFileSystemInterface*> ProvidedFileSystemMap;
-  typedef std::map<std::string, int> MountPointNameToIdMap;
+  // Key is a pair of an extension id and file system id, which makes it
+  // unique among the entire service instance.
+  typedef std::pair<std::string, std::string> FileSystemKey;
+
+  typedef std::map<FileSystemKey, ProvidedFileSystemInterface*>
+      ProvidedFileSystemMap;
+  typedef std::map<std::string, FileSystemKey> MountPointNameToKeyMap;
 
   // Called when the providing extension accepts or refuses a unmount request.
   // If |error| is equal to FILE_OK, then the request is accepted.
@@ -111,8 +119,7 @@ class Service : public KeyedService,
   FileSystemFactoryCallback file_system_factory_;
   ObserverList<Observer> observers_;
   ProvidedFileSystemMap file_system_map_;  // Owns pointers.
-  MountPointNameToIdMap mount_point_name_to_id_map_;
-  int next_id_;
+  MountPointNameToKeyMap mount_point_name_to_key_map_;
   base::WeakPtrFactory<Service> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Service);