Add shutdown() to providers.

They're needed for unit tests.
I was hoping this would solve some of the unit test issues, but it didn't look
like so.  But still they're nice to have.

Change-Id: Ibf6ae78055560d27aac5934d567a17084de99d84

src/com/android/email/provider/AttachmentProvider.java

@@ -478,4 +478,12 @@ public class AttachmentProvider extends ContentProvider {
             c.close();
         }
     }
+
+    /**
+     * Need this to suppress warning in unit tests.
+     */
+    @Override
+    public void shutdown() {
+        // Don't call super.shutdown(), which emits a warning...
+    }
 }

src/com/android/email/provider/EmailProvider.java

@@ -635,6 +635,19 @@ public class EmailProvider extends ContentProvider {
         return helper.getReadableDatabase();
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public void shutdown() {
+        if (mDatabase != null) {
+            mDatabase.close();
+            mDatabase = null;
+        }
+        if (mBodyDatabase != null) {
+            mBodyDatabase.close();
+            mBodyDatabase = null;
+        }
+    }
+
     /*package*/ static void deleteOrphans(SQLiteDatabase database, String tableName) {
         if (database != null) {
             // We'll look at all of the items in the table; there won't be many typically