Don't start search from a dialog if there is no activity associated with

the search manager at that point.

Still works:
- hitting search when a managed dialog of an app is showing will dismiss
  the dialog and start in-app search (if it supports it), falling back
  on global search
- hitting search when a dialog of an app (not managed by the activity) will
  dismiss the dialog and start global search
- hitting search when a system dialog is showing will just dismiss the dialog.

core/java/android/app/Dialog.java

@@ -788,6 +788,11 @@ public class Dialog implements DialogInterface, Window.Callback,
         final SearchManager searchManager = (SearchManager) mContext
                 .getSystemService(Context.SEARCH_SERVICE);
 
+        // can't start search without an associated activity (e.g a system dialog)
+        if (!searchManager.hasIdent()) {
+            return false;
+        }
+
         // associate search with owner activity if possible (otherwise it will default to
         // global search).
         final ComponentName appName = mOwnerActivity == null ? null

core/java/android/app/SearchManager.java

@@ -1536,6 +1536,10 @@ public class SearchManager
         mService = ISearchManager.Stub.asInterface(
                 ServiceManager.getService(Context.SEARCH_SERVICE));
     }
+
+    /*package*/ boolean hasIdent() {
+        return mIdent != 0;
+    }
     
     /*package*/ void setIdent(int ident) {
         if (mIdent != 0) {