MB: Enable optimize_for_fuzzing=true for libfuzzer builds.

tools-webrtc/mb/mb_config.pyl

 # Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 # FOR DETAILS ON THIS FILE SEE THE MAIN COPY IN //tools/mb/mb_config.pyl.
 # This is configuration for standalone WebRTC bots. It is used to keep the bot
@@ skipping 219 matching lines @@
     'release_bot_x64': [
       'gn', 'openh264_release_bot', 'x64'
     ],
     'perf_release_bot_x86': [
       'gn', 'openh264', 'release', 'static', 'goma', 'x86'
     ],
     'perf_release_bot_x64': [
       'gn', 'openh264', 'release', 'static', 'goma', 'x64'
     ],
     'libfuzzer_asan_release_bot_x64': [
-      'libfuzzer', 'asan', 'openh264_release_bot', 'x64'
+      'libfuzzer', 'asan', 'optimize_for_fuzzing', 'openh264_release_bot', 'x64'
     ],
     'memcheck_release_bot_x64': [
       'memcheck', 'gn', 'openh264_release_bot', 'x64'
     ],
 
     # Windows
     'win_clang_debug_bot_x86': [
       'gn', 'clang', 'openh264_debug_bot', 'x86',
     ],
     'win_clang_release_bot_x86': [
@@ skipping 158 matching lines @@
     },
 
     'openh264_debug_bot': {
       'mixins': ['openh264', 'debug_bot'],
     },
 
     'openh264_release_bot': {
       'mixins': ['openh264', 'release_bot'],
     },
 
+    'optimize_for_fuzzing': {
+      'gn_args': 'optimize_for_fuzzing=true',
+    },
+
     'release': {
       'gn_args': 'is_debug=false',
     },
 
     'release_bot': {
       'mixins': ['release', 'static', 'dcheck_always_on', 'goma'],
     },
 
     'shared': {
       'gn_args': 'is_component_build=true',
@@ skipping 21 matching lines @@
 
     'x64': {
       'gn_args': 'target_cpu="x64"',
     },
 
     'x86': {
       'gn_args': 'target_cpu="x86"',
     },
   },
 }