Add a method to remount all removable devices in DiskMountManager.

chrome/browser/chromeos/file_manager/fake_disk_mount_manager.cc

Index: chrome/browser/chromeos/file_manager/fake_disk_mount_manager.cc
diff --git a/chrome/browser/chromeos/file_manager/fake_disk_mount_manager.cc b/chrome/browser/chromeos/file_manager/fake_disk_mount_manager.cc
index 77f5bd9d1e7c9a597b3bb7c2319fd144d3a4d555..8f7fb4d7d50b639505819f20aaac32428ed5cd43 100644
--- a/chrome/browser/chromeos/file_manager/fake_disk_mount_manager.cc
+++ b/chrome/browser/chromeos/file_manager/fake_disk_mount_manager.cc
@@ -28,6 +28,10 @@ FakeDiskMountManager::UnmountRequest::UnmountRequest(
       options(options) {
 }
 
+FakeDiskMountManager::RemountAllRequest::RemountAllRequest(
+    chromeos::MountAccessMode access_mode)
+    : access_mode(access_mode) {}
+
 FakeDiskMountManager::FakeDiskMountManager() {
 }
 
@@ -108,6 +112,11 @@ void FakeDiskMountManager::UnmountPath(const std::string& mount_path,
   pending_unmount_callbacks_.push(callback);
 }
 
+void FakeDiskMountManager::RemountAllRemovableDrives(
+    chromeos::MountAccessMode access_mode) {
+  remount_all_requests_.push_back(RemountAllRequest(access_mode));
+}
+
 bool FakeDiskMountManager::FinishAllUnmountPathRequests() {
   if (pending_unmount_callbacks_.empty())
     return false;