Enable building with Native Client.

This requires you don't have target_os=["ios"] set in your
libyuv root .gclient file, since that will make native_client not
being downloaded due to
https://code.google.com/p/chromium/codesearch#chromium/src/DEPS&l=357

BUG=libyuv:573
TESTED=
rm chromium/.last_sync_chromium
rm chromium/.gclient.tmp_entries
gclient sync
native_client/build/gyp_nacl all.gyp -Dgtest_target_type=executable -Dmsan=0 -Duse_system_yasm=0
ninja -C out/Debug

Review URL: https://codereview.chromium.org/1845003004 .

.gitignore

@@ -9,6 +9,8 @@ pin-log.txt
 /chromium/src/
 /google_apis
 /links
+/links.db
+/native_client
 /net
 /out
 /sde-avx-sse-transition-out.txt

chromium/.gclient

@@ -5,7 +5,6 @@ solutions = [{
   'managed': False,
   'custom_deps': {
     # Skip syncing some large dependencies Libyuv will never need.
-    'src/native_client': None,
     'src/third_party/cld_2/src': None,
     'src/third_party/ffmpeg': None,
     'src/third_party/hunspell_dictionaries': None,

setup_links.py

@@ -35,6 +35,7 @@ DIRECTORIES = [
   'build',
   'buildtools',
   'google_apis',  # Needed by build/common.gypi.
+  'native_client',
   'net',
   'testing',
   'third_party/binutils',

sync_chromium.py

@@ -86,8 +86,6 @@ def main():
   env = os.environ.copy()
 
   # Avoid downloading NaCl toolchain as part of the Chromium hooks.
-  env.setdefault('GYP_DEFINES', '')
-  env['GYP_DEFINES'] += ' disable_nacl=1'
   env['GYP_CHROMIUM_NO_ACTION'] = '1'
   gclient_cmd = 'gclient.bat' if sys.platform.startswith('win') else 'gclient'
   args = [