[Offline Pages] Add a GCMAppHandler for offline page prefetch.

components/offline_pages/core/prefetch/prefetch_service_impl.h

Index: components/offline_pages/core/prefetch/prefetch_service_impl.h
diff --git a/components/offline_pages/core/prefetch/prefetch_service_impl.h b/components/offline_pages/core/prefetch/prefetch_service_impl.h
index 69346aa356ad721f13d34b818cdb714cced3531d..ebcb6f844eb880c2b77c6427fcf1da3be383998e 100644
--- a/components/offline_pages/core/prefetch/prefetch_service_impl.h
+++ b/components/offline_pages/core/prefetch/prefetch_service_impl.h
@@ -14,7 +14,15 @@ namespace offline_pages {
 
 class PrefetchServiceImpl : public PrefetchService {
  public:
-  PrefetchServiceImpl();
+  // An interface allowing the prefetch service to hold a GCM App Handler for
+  // lifetime purposes. TODO(dewittj): Add an interface method for getting an
+  // InstandID token.
+  class GCMAppHandler {

[Dmitry Titov, 2017/05/16 19:33:23]

Does it deserve a separate file? Most of the subobjects of PS (Zine, Dispatcher,
etc) will have a separate declaration, perhaps it's better to just use one way
of creating those subobjects.

[fgorski, 2017/05/16 20:03:02]

If this is only about life cycle, why not user data?

If this is going to be extended to provide interface to the functionality I am
OK with that.

[dewittj, 2017/05/16 22:58:22]

Added TODO and left interface here.

+   public:
+    virtual ~GCMAppHandler() = default;
+  };
+
+  PrefetchServiceImpl(std::unique_ptr<GCMAppHandler> gcm_app_handler);

[fgorski, 2017/05/16 20:03:01]

explicit in case you stick with the interface

[dewittj, 2017/05/16 22:58:22]

Done.

   ~PrefetchServiceImpl() override;
 
   // PrefetchService implementation:
@@ -29,6 +37,8 @@ class PrefetchServiceImpl : public PrefetchService {
   void Shutdown() override;
 
  private:
+  std::unique_ptr<GCMAppHandler> gcm_app_handler_;
+
   DISALLOW_COPY_AND_ASSIGN(PrefetchServiceImpl);
 };