MB: Add symbol_level=2 to new Win ASan bot.

Hopefully that will give better error traces than just a memory
address upon failure.

BUG=chromium:677380
TBR=ehmaldonado@webrtc.org

Review-Url: https://codereview.webrtc.org/2604163002 .
Cr-Commit-Position: refs/heads/master@{#15830}
diff --git a/tools-webrtc/mb/mb_config.pyl b/tools-webrtc/mb/mb_config.pyl
index 251eb44..9d6b1a1 100644
--- a/tools-webrtc/mb/mb_config.pyl
+++ b/tools-webrtc/mb/mb_config.pyl
@@ -259,7 +259,7 @@
       'gn', 'clang', 'openh264_release_bot', 'x64',
     ],
     'win_asan_clang_release_bot_x86': [
-      'gn', 'asan', 'clang', 'openh264_release_bot', 'x86',
+      'gn', 'asan', 'clang',  'full_symbols', 'openh264_release_bot', 'x86',
     ],
     'win_syzyasan_release_bot_x86': [
       'gn', 'syzyasan', 'minimal_symbols', 'openh264_release_bot', 'x86',
@@ -366,6 +366,10 @@
       'gn_args': 'error',
     },
 
+    'full_symbols': {
+      'gn_args': 'symbol_level=2',
+    },
+
     'gcc': {
       'gn_args': 'is_clang=false use_sysroot=false',
     },