ZIP mount: Fix unhandled MOUNT_TYPE_INVALID error

When trying to mount a ZIP archive with an invalid path, cros_disks
sends back a signal to the browser with source_type=MOUNT_TYPE_INVALID.
The observing VolumeManager doesn't handle this source/mount_type, and
the archive mounting request initiated from the UI is never resolved.

Fix this by removing the distinction between MOUNT_TYPE_INVALID and the
other mount error types.

Bug: 1136329
Change-Id: If807a854ef7a13635ded29a38e76ee54e057bfc8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2560443Reviewed-by: Sergei Datsenko <dats@chromium.org>
Reviewed-by: François Degros <fdegros@chromium.org>
Commit-Queue: Jeremie Boulic <jboulic@chromium.org>
Commit-Queue: François Degros <fdegros@chromium.org>
Cr-Commit-Position: refs/heads/master@{#831221}

chrome/browser/chromeos/file_manager/volume_manager.cc

@@ -901,36 +901,24 @@ void VolumeManager::OnMountEvent(
     chromeos::MountError error_code,
     const chromeos::disks::DiskMountManager::MountPointInfo& mount_info) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  switch (mount_info.mount_type) {
-    case chromeos::MOUNT_TYPE_ARCHIVE:
-    case chromeos::MOUNT_TYPE_DEVICE: {
-      // Notify a mounting/unmounting event to observers.
-      const chromeos::disks::Disk* const disk =
-          disk_mount_manager_->FindDiskBySourcePath(mount_info.source_path);
-      std::unique_ptr<Volume> volume =
-          Volume::CreateForRemovable(mount_info, disk);
-      switch (event) {
-        case chromeos::disks::DiskMountManager::MOUNTING: {
-          DoMountEvent(error_code, std::move(volume));
-          return;
-        }
-        case chromeos::disks::DiskMountManager::UNMOUNTING:
-          DoUnmountEvent(error_code, *volume);
-          return;
-      }
-      NOTREACHED();
-    }
-
-    // Network storage is responsible for doing its own mounting.
-    case chromeos::MOUNT_TYPE_NETWORK_STORAGE: {
-      break;
-    }
+  // Network storage is responsible for doing its own mounting.
+  if (mount_info.mount_type == chromeos::MOUNT_TYPE_NETWORK_STORAGE)
+    return;
 
-    case chromeos::MOUNT_TYPE_INVALID: {
-      NOTREACHED();
-      break;
+  // Notify a mounting/unmounting event to observers.
+  const chromeos::disks::Disk* const disk =
+      disk_mount_manager_->FindDiskBySourcePath(mount_info.source_path);
+  std::unique_ptr<Volume> volume = Volume::CreateForRemovable(mount_info, disk);
+  switch (event) {
+    case chromeos::disks::DiskMountManager::MOUNTING: {
+      DoMountEvent(error_code, std::move(volume));
+      return;
     }
+    case chromeos::disks::DiskMountManager::UNMOUNTING:
+      DoUnmountEvent(error_code, *volume);
+      return;
   }
+  NOTREACHED();
 }
 
 void VolumeManager::OnFormatEvent(