mediaview: Mount ARC documents provider file system volumes.

chrome/browser/chromeos/arc/arc_service_launcher.cc

Index: chrome/browser/chromeos/arc/arc_service_launcher.cc
diff --git a/chrome/browser/chromeos/arc/arc_service_launcher.cc b/chrome/browser/chromeos/arc/arc_service_launcher.cc
index 599eee60b0619d3d14121d99bda80c245e6300d9..f7a330eb9d43b05c4c55b744cdd80fc0011842a1 100644
--- a/chrome/browser/chromeos/arc/arc_service_launcher.cc
+++ b/chrome/browser/chromeos/arc/arc_service_launcher.cc
@@ -98,8 +98,14 @@ void ArcServiceLauncher::Initialize() {
       base::MakeUnique<ArcBootPhaseMonitorBridge>(arc_bridge_service));
   arc_service_manager_->AddService(
       base::MakeUnique<ArcClipboardBridge>(arc_bridge_service));
-  arc_service_manager_->AddService(
-      base::MakeUnique<ArcFileSystemService>(arc_bridge_service));
+  auto file_system_service =
+      base::MakeUnique<ArcFileSystemService>(arc_bridge_service);
+  // We don't have to call ArcFileSystemService::RemoveObserver() in
+  // ~ArcServiceManager() since the observer in ArcServiceManager always
+  // outlives the ArcFileSystemService object.
+  file_system_service->AddObserver(

[Luis Héctor Chávez, 2017/01/10 05:49:04]

This looks kind of weird. Can we either:

a) Preferred: create a small interface in components/arc that has
Add/RemoveObserver(ArcFileSystemObserver*), and have ArcServiceManager expose
that directly so that the volume_manager can subscribe to ArcFileSystemObserver
events directly instead of ArcServiceManager re-emit all the events, which does
not scale well and might get out of hand if you want to add more events. This
might become easier and less boilerplatey if we land something like
https://codereview.chromium.org/2622843002
a) Make this a Delegate instead so we can pass it to ArcFileSystemService's
constructor.

+      arc_service_manager_->file_system_observer());
+  arc_service_manager_->AddService(std::move(file_system_service));
   arc_service_manager_->AddService(base::MakeUnique<ArcCrashCollectorBridge>(
       arc_bridge_service, arc_service_manager_->blocking_task_runner()));
   arc_service_manager_->AddService(