Give the BackgroundFetchJobController a simple state.

content/browser/background_fetch/background_fetch_job_controller.h

Index: content/browser/background_fetch/background_fetch_job_controller.h
diff --git a/content/browser/background_fetch/background_fetch_job_controller.h b/content/browser/background_fetch/background_fetch_job_controller.h
index 5d4fdcc7f006abfde28b6c958df77fa485ed549b..eac97eff46b74f0a2de7a7463b1ba2169c1741b6 100644
--- a/content/browser/background_fetch/background_fetch_job_controller.h
+++ b/content/browser/background_fetch/background_fetch_job_controller.h
@@ -30,9 +30,10 @@ class StoragePartition;
 class CONTENT_EXPORT BackgroundFetchJobController
     : public DownloadItem::Observer {
  public:
+  enum class State { INITIALIZED, FETCHING, ABORTED, COMPLETED };
+
   using CompletedCallback =
-      base::OnceCallback<void(const BackgroundFetchRegistrationId&,
-                              bool /* aborted_by_developer */)>;
+      base::OnceCallback<void(BackgroundFetchJobController*)>;

[harkness, 2017/03/28 14:55:43]

optional: personally, I would have this callback return registrationId and
state, since the first thing the caller does is query for registrationId and
state, and we can look up the JobController given the registrationId.

[Peter Beverloo, 2017/03/29 13:05:22]

I'm keeping this as-is for now. We can reduce the given information later if we
can, which I'd be in favor of, but depending on where we take the JobController
that may still change. Let's iterate on it as part of the other CL.

 
   BackgroundFetchJobController(
       const BackgroundFetchRegistrationId& registration_id,
@@ -57,6 +58,9 @@ class CONTENT_EXPORT BackgroundFetchJobController
   // Called by the BackgroundFetchContext when the system is shutting down.
   void Shutdown();
 
+  // Returns the current state of this Job Controller.
+  State state() const { return state_; }
+
   // Returns the registration id for which this job is fetching data.
   const BackgroundFetchRegistrationId& registration_id() const {
     return registration_id_;
@@ -84,6 +88,9 @@ class CONTENT_EXPORT BackgroundFetchJobController
   // Options for the represented background fetch registration.
   BackgroundFetchOptions options_;
 
+  // The current state of this Job Controller.
+  State state_ = State::INITIALIZED;
+
   // TODO(peter): Deprecated, remove in favor of |registration_id|.
   std::string job_guid_;