p2p: Remove IsP2PAllowedForInteractiveChecks() function and its users

This is no longer needed now that it's possible to just pass
-interactive=false to the update_engine_client program.

BUG=chromium:273251
TEST=Manually tested + unit tests pass.

Change-Id: If8b1d600125d7a3108a81471dbcd2f9ca00a6988
Reviewed-on: https://chromium-review.googlesource.com/168446
Reviewed-by: David Zeuthen <zeuthen@chromium.org>
Tested-by: David Zeuthen <zeuthen@chromium.org>
Commit-Queue: David Zeuthen <zeuthen@chromium.org>
diff --git a/update_attempter.cc b/update_attempter.cc
index 72d77c9..ea1c619 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -241,18 +241,8 @@
         LOG(INFO) << "Non-interactive check - allowing p2p for downloading";
         use_p2p_for_downloading = true;
       } else {
-        // TODO(zeuthen,chromium:273251): Remove this marker once we
-        // can easily trigger non-interactive checks.
-        if (utils::IsP2PAllowedForInteractiveChecks()) {
-          LOG(INFO) << "Found marker file at "
-                    << kP2PAllowInteractiveMarkerFile
-                    << " - allowing p2p for downloading despite the fact"
-                    << " the attempt is interactive.";
-          use_p2p_for_downloading = true;
-        } else {
-          LOG(INFO) << "Forcibly disabling use of p2p for downloading "
-                    << "since this update attempt is interactive.";
-        }
+        LOG(INFO) << "Forcibly disabling use of p2p for downloading "
+                  << "since this update attempt is interactive.";
       }
     }
   }