Adds the contextMessage field to notifications.

ui/message_center/cocoa/notification_controller_unittest.mm

Index: ui/message_center/cocoa/notification_controller_unittest.mm
diff --git a/ui/message_center/cocoa/notification_controller_unittest.mm b/ui/message_center/cocoa/notification_controller_unittest.mm
index 87aced2fc8ca3ec255ca352f8a03665d120cb800..fb6a7dea90ba6eb391cee7e7de4443abcb4a085a 100644
--- a/ui/message_center/cocoa/notification_controller_unittest.mm
+++ b/ui/message_center/cocoa/notification_controller_unittest.mm
@@ -84,6 +84,10 @@ class MockMessageCenter : public message_center::FakeMessageCenter {
   return message_.get();
 }
 
+- (NSTextField*)contextMessageView {
+  return contextMessage_.get();
+}
+
 - (NSView*)listItemView {
   return listItemView_.get();
 }
@@ -272,6 +276,7 @@ TEST_F(NotificationControllerTest, List) {
       UTF8ToUTF16("Second title"),
       UTF8ToUTF16("second slightly longer message"));
   optional.items.push_back(item2);
+  optional.context_message = UTF8ToUTF16("Context Message");
 
   scoped_ptr<message_center::Notification> notification(
       new message_center::Notification(
@@ -293,6 +298,7 @@ TEST_F(NotificationControllerTest, List) {
 
   EXPECT_FALSE([[controller titleView] isHidden]);
   EXPECT_TRUE([[controller messageView] isHidden]);
+  EXPECT_FALSE([[controller contextMessageView] isHidden]);
 
   EXPECT_EQ(2u, [[[controller listItemView] subviews] count]);
   EXPECT_LT(NSMaxY([[controller listItemView] frame]),