Add ios_code_signing_identity_description to GN args.

TBR=courtneyfe@webrtc.org

Bug: webrtc:11591
Change-Id: I1706905086d97d66230000d10e09f4ec02e07eb5
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/175803
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31335}

tools_webrtc/mb/mb_config.pyl

diff --git a/tools_webrtc/mb/mb_config.pyl b/tools_webrtc/mb/mb_config.pyl
index 059c724..9f9fdd2 100644
--- a/tools_webrtc/mb/mb_config.pyl
+++ b/tools_webrtc/mb/mb_config.pyl
@@ -404,13 +404,16 @@
       'ios', 'release_bot', 'arm64', 'no_ios_code_signing', 'ios_use_goma_rbe'
     ],
     'ios_internal_debug_bot_arm64': [
-      'ios', 'debug_bot', 'arm64', 'ios_use_goma_rbe'
+      'ios', 'debug_bot', 'arm64', 'ios_use_goma_rbe',
+      'ios_code_signing_identity_description',
     ],
     'ios_internal_release_bot_arm64': [
-      'ios', 'release_bot', 'arm64', 'ios_use_goma_rbe'
+      'ios', 'release_bot', 'arm64', 'ios_use_goma_rbe',
+      'ios_code_signing_identity_description',
     ],
     'ios_internal_pure_release_bot_arm64': [
-      'ios', 'pure_release_bot', 'arm64', 'ios_use_goma_rbe'
+      'ios', 'pure_release_bot', 'arm64', 'ios_use_goma_rbe',
+      'ios_code_signing_identity_description',
     ],
     'ios_debug_bot_x64': [
       'ios', 'debug_bot', 'x64', 'ios_use_goma_rbe'
@@ -506,6 +509,10 @@
       'gn_args': 'use_goma=true',
     },
 
+    'ios_code_signing_identity_description': {
+      'gn_args': 'ios_code_signing_identity_description="Apple Development"',
+    },
+
     'ios_use_goma_rbe': {
       'gn_args': 'ios_use_goma_rbe=true',
     },