>>> Configuring source in /var/tmp/portage/www-client/chromium-87.0.4278.0/work/chromium-87.0.4278.0 ...
 * Using python2.7 to build
 * Configuring Chromium...
gn gen --args= is_clang=true clang_use_chrome_plugins=false custom_toolchain="//build/toolchain/linux/unbundle:default" host_toolchain="//build/toolchain/linux/unbundle:default" is_debug=false is_component_build=false use_allocator="tcmalloc" enable_nacl=false use_system_harfbuzz=true use_gnome_keyring=false enable_js_type_check=true enable_hangout_services_extension=true enable_widevine=true use_cups=true use_kerberos=false use_pulseaudio=true use_vaapi=true fieldtrial_testing_like_official_build=true use_gold=false use_sysroot=false use_custom_libcxx=false use_lld=false proprietary_codecs=true ffmpeg_branding="Chrome" google_api_key="AIzaSyDEAOvatFo0eTgsV_ZlEzx0ObmepsMzfAc" google_default_client_id="329227923882.apps.googleusercontent.com" google_default_client_secret="vgKG0NNv7GoDpbtoFNLxCUXu" target_cpu="x64" treat_warnings_as_errors=false fatal_linker_warnings=false icu_use_data_file=false use_ozone=false is_official_build=true is_cfi=false  out/Release
ERROR at //build/config/compiler/pgo/BUILD.gn:58:35: Script returned non-zero exit code.
      pgo_data_path = rebase_path(exec_script("//tools/update_pgo_profiles.py",
                                  ^----------
Current dir: /var/tmp/portage/www-client/chromium-87.0.4278.0/work/chromium-87.0.4278.0/out/Release/
Command: python /var/tmp/portage/www-client/chromium-87.0.4278.0/work/chromium-87.0.4278.0/tools/update_pgo_profiles.py --target linux get_profile_path
Returned 1.
stderr:

Traceback (most recent call last):
  File "/var/tmp/portage/www-client/chromium-87.0.4278.0/work/chromium-87.0.4278.0/tools/update_pgo_profiles.py", line 154, in <module>
    sys.exit(main())
  File "/var/tmp/portage/www-client/chromium-87.0.4278.0/work/chromium-87.0.4278.0/tools/update_pgo_profiles.py", line 150, in main
    return args.func(args)
  File "/var/tmp/portage/www-client/chromium-87.0.4278.0/work/chromium-87.0.4278.0/tools/update_pgo_profiles.py", line 122, in _get_profile_path
    profile_path)
RuntimeError: requested profile "/var/tmp/portage/www-client/chromium-87.0.4278.0/work/chromium-87.0.4278.0/chrome/build/pgo_profiles/chrome-linux-master-1601358844-b8defbe977309018021c72a700e18c84f94d16d4.profdata" doesn't exist, please make sure "checkout_pgo_profiles" is set to True in the "custom_vars" section of your .gclient file, e.g.:
solutions = [
  {
    "name": "src",
    # ...
    "custom_vars": {
      "checkout_pgo_profiles": True,
    },
  },
],
and then run "gclient runhooks" to download it. You can also simply disable the PGO optimizations by setting |chrome_pgo_phase = 0| in your GN arguments.