have "search" as the reason when dismissing system dialogs for search.

this way search can't dismiss itself.  can't use the constant because it is
in policy.  would rather leave it this way instead of moving constants for
system dialog dismissal to framework.
diff --git a/policy/com/android/internal/policy/impl/PhoneWindow.java b/policy/com/android/internal/policy/impl/PhoneWindow.java
index d2d1421..db43a9c 100644
--- a/policy/com/android/internal/policy/impl/PhoneWindow.java
+++ b/policy/com/android/internal/policy/impl/PhoneWindow.java
@@ -2510,7 +2510,7 @@
         if (cb == null) {
             return false;
         } else {
-            sendCloseSystemWindows();
+            sendCloseSystemWindows("search");
             return cb.onSearchRequested();
         }
     }