ios_clang_device_tot: Use correct signing cert.

Bug: 1085394
Change-Id: I0f4c9def4906f7a7f1e964c7cf45e208504ae3e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2212488
Auto-Submit: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#771191}

tools/mb/mb_config.pyl

@@ -1887,7 +1887,7 @@
     ],
 
     'ios_clang_device_tot': [
-      'clang_tot', 'ios_device', 'release',
+      'clang_tot', 'ios_device', 'release', 'ios_chromium_cert'
     ],
 
     'ios_cronet': [
@@ -2586,6 +2586,11 @@
       'gn_args': 'target_os="ios"',
     },
 
+    'ios_chromium_cert': {
+      # defaults to "Apple Development" under ios_sdk.gni
+      'gn_args': 'ios_code_signing_identity_description=\"iPhone Developer\"',
+    },
+
     'ios_deployment_target_9_0': {
       'gn_args': 'ios_deployment_target=\"9.0\"',
     },