Messaging: Properly hide and show FAB

When starting or stopping action mode, the FAB should hide and show again

Change-Id: I94b12cbd3190df90189dc02c39ac7db78d58d090

src/com/android/messaging/ui/conversationlist/AbstractConversationListActivity.java

@@ -72,6 +72,7 @@ public abstract class AbstractConversationListActivity extends BugleActionBarAct
 
     protected void startMultiSelectActionMode() {
         startActionMode(new MultiSelectActionModeCallback(this));
+        mConversationListFragment.dismissFab();
     }
 
     protected void exitMultiSelectState() {