p2p: Make P2PManager available from the SystemState singleton

BUG=chromium:260426
TEST=Unit tests pass
Change-Id: Iadaa531d631c8d7268f35d512ff33f8d53e1cc5e
Reviewed-on: https://chromium-review.googlesource.com/64828
Reviewed-by: David Zeuthen <zeuthen@chromium.org>
Commit-Queue: David Zeuthen <zeuthen@chromium.org>
Tested-by: David Zeuthen <zeuthen@chromium.org>
diff --git a/system_state.h b/system_state.h
index 08092f1..f4bd19c 100644
--- a/system_state.h
+++ b/system_state.h
@@ -24,6 +24,7 @@
 class PayloadStateInterface;
 class GpioHandler;
 class UpdateAttempter;
+class P2PManager;
 
 // An interface to global system context, including platform resources,
 // the current state of the system, high-level objects whose lifetime is same
@@ -83,6 +84,9 @@
   // common to all Omaha requests.
   virtual OmahaRequestParams* request_params() = 0;
 
+  // Returns a pointer to the P2PManager singleton.
+  virtual P2PManager* p2p_manager() = 0;
+
   // If true, this is the first instance of the update engine since the system
   // restarted. Important for tracking whether you are running instance of the
   // update engine on first boot or due to a crash/restart.