Update the payload public key location in Android.

In Android builds, the payload public key is installed in a different
location.

Bug: 23937688
Test: emerge-link update_engine; `mm`

Change-Id: Ic3a661e041a5709c116b6acd0d082a37b8bfe5df
diff --git a/omaha_response_handler_action.cc b/omaha_response_handler_action.cc
index dba3d74..1153628 100644
--- a/omaha_response_handler_action.cc
+++ b/omaha_response_handler_action.cc
@@ -40,16 +40,13 @@
 
 OmahaResponseHandlerAction::OmahaResponseHandlerAction(
     SystemState* system_state)
-    : system_state_(system_state),
-      got_no_update_response_(false),
-      key_path_(DeltaPerformer::kUpdatePayloadPublicKeyPath),
-      deadline_file_(kDeadlineFile) {}
+    : OmahaResponseHandlerAction(system_state, kDeadlineFile) {}
 
 OmahaResponseHandlerAction::OmahaResponseHandlerAction(
     SystemState* system_state, const string& deadline_file)
     : system_state_(system_state),
       got_no_update_response_(false),
-      key_path_(DeltaPerformer::kUpdatePayloadPublicKeyPath),
+      key_path_(constants::kUpdatePayloadPublicKeyPath),
       deadline_file_(deadline_file) {}
 
 void OmahaResponseHandlerAction::PerformAction() {