Don't crash if no email provider active

The content resolver throws an exception if no email provider is active.
Handle this case without crashing.

Bug:14273233
Change-Id: I67c6e36ed7d664e46b71410ab1a81002bd3eb3b5
diff --git a/src/com/android/exchange/Exchange.java b/src/com/android/exchange/Exchange.java
index 2b2a468..c18c86c 100644
--- a/src/com/android/exchange/Exchange.java
+++ b/src/com/android/exchange/Exchange.java
@@ -31,7 +31,12 @@
     public void onCreate() {
         super.onCreate();
         EmailContent.init(this);
-        getContentResolver().call(EmailContent.CONTENT_URI, MailboxUtilities.FIX_PARENT_KEYS_METHOD,
-                "", null);
+        try {
+            getContentResolver().call(EmailContent.CONTENT_URI,
+                    MailboxUtilities.FIX_PARENT_KEYS_METHOD, "", null);
+        } catch (IllegalArgumentException e) {
+            // If there is no Email provider (which happens if eg the
+            // Email app is disabled), ignore.
+        }
     }
 }