run_on_app: For D8, make default type = proguarded

Bug:
Change-Id: Ibffc4d76fc695b000b718220bffd9bf42b55c32b
diff --git a/tools/run_on_app.py b/tools/run_on_app.py
index 480774f..9b4cb4d 100755
--- a/tools/run_on_app.py
+++ b/tools/run_on_app.py
@@ -28,8 +28,7 @@
                     default='gmscore',
                     choices=APPS)
   result.add_option('--type',
-                    help='',
-                    default='deploy',
+                    help='Default for R8: deploy, for D8: proguarded',
                     choices=TYPES)
   result.add_option('--out',
                     help='',
@@ -104,6 +103,10 @@
 
   version = data.VERSIONS[options.version]
 
+  if not options.type:
+    options.type = 'deploy' if options.compiler == 'r8' \
+        else 'proguarded'
+
   if options.type not in version:
     print 'No type %s for version %s' % (options.type, options.version)
     print 'Valid types are %s' % version.keys()