app_dial: Enable early-media video

Certain applications (e.g. door-phone) require that also video is transmitted
before a call is accepted.

Change-Id: I9842e1dc2f6e1c2c49dc33fe615255007d2f821e

UPGRADE.txt

@@ -23,6 +23,14 @@
 === UPGRADE-14.txt  -- Upgrade info for 13 to 14
 ===========================================================
 
+From 15.3.0 to 15.4.0:
+
+app_dial
+------------------
+ * The Dial application now supports early-media video (in addition to
+   audio) on both the calling as well as the called party.
+   Be aware that this is a change in behavior.
+
 From 15.2.0 to 15.3.0:
 
 app_confbridge

apps/app_dial.c

@@ -1601,6 +1601,7 @@ static struct ast_channel *wait_for_answer(struct ast_channel *in,
 					break;
 				}
 				break;
+			case AST_FRAME_VIDEO:
 			case AST_FRAME_VOICE:
 			case AST_FRAME_IMAGE:
 				if (caller_entertained) {
@@ -1699,6 +1700,7 @@ static struct ast_channel *wait_for_answer(struct ast_channel *in,
 						ast_log(LOG_WARNING, "Unable to send URL\n");
 					}
 					break;
+				case AST_FRAME_VIDEO:
 				case AST_FRAME_VOICE:
 				case AST_FRAME_IMAGE:
 					if (!single || caller_entertained) {