Add discard drafts capability.

Bug: 10098652
Change-Id: Ib9ae05b9c460667a554e87e44715c58c817cead3
diff --git a/src/com/android/exchange/service/EmailSyncAdapterService.java b/src/com/android/exchange/service/EmailSyncAdapterService.java
index 0096acc..20b95ac 100644
--- a/src/com/android/exchange/service/EmailSyncAdapterService.java
+++ b/src/com/android/exchange/service/EmailSyncAdapterService.java
@@ -346,12 +346,14 @@
                         AccountCapabilities.SANITIZED_HTML |
                         AccountCapabilities.SMART_REPLY |
                         AccountCapabilities.SERVER_SEARCH |
-                        AccountCapabilities.UNDO;
+                        AccountCapabilities.UNDO |
+                        AccountCapabilities.DISCARD_CONVERSATION_DRAFTS;
             } else {
                 return AccountCapabilities.SYNCABLE_FOLDERS |
                         AccountCapabilities.SANITIZED_HTML |
                         AccountCapabilities.SMART_REPLY |
-                        AccountCapabilities.UNDO;
+                        AccountCapabilities.UNDO |
+                        AccountCapabilities.DISCARD_CONVERSATION_DRAFTS;
             }
         }