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

chrome/browser/chromeos/file_manager/volume_manager.cc

Index: chrome/browser/chromeos/file_manager/volume_manager.cc
diff --git a/chrome/browser/chromeos/file_manager/volume_manager.cc b/chrome/browser/chromeos/file_manager/volume_manager.cc
index 5631359fab7b560aa9191b403f89bd8f76bbf766..ce45a8483ee9783167422fb76ddfa5a79afaa7b4 100644
--- a/chrome/browser/chromeos/file_manager/volume_manager.cc
+++ b/chrome/browser/chromeos/file_manager/volume_manager.cc
@@ -239,12 +239,12 @@ std::string GetMountPointNameForMediaStorage(
 }  // namespace
 
 VolumeInfo::VolumeInfo()
-    : file_system_id(0),
-      type(VOLUME_TYPE_GOOGLE_DRIVE),
+    : type(VOLUME_TYPE_GOOGLE_DRIVE),
       device_type(chromeos::DEVICE_TYPE_UNKNOWN),
       mount_condition(chromeos::disks::MOUNT_CONDITION_NONE),
       is_parent(false),
-      is_read_only(false) {}
+      is_read_only(false) {
+}
 
 VolumeInfo::~VolumeInfo() {
 }