mac: Use ninja by default.

With this change, `gclient runhooks` creates ninja files by default on Mac.
To build, run `ninja -C out/Release chrome`. The output appears in out/
instead of in xcodebuild/. (This doesn't happen if OS=ios, so it shouldn't
affect chrome/ios development.)

If you need to use xcode for some reason, you can
`export GYP_GENERATORS=xcode` to force xcode project generation.
If you do this, please inform me why.

Bots should automatically pick up the binaries in the new location (out).
If something does break, it should be safe to revert this change, and bots
should then automatically go back to picking up binaries from the old
location (xcodebuild).

BUG=294387
R=mark@chromium.org

Review URL: https://codereview.chromium.org/31143002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@231675 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

gyp_chromium

@@ -138,11 +138,15 @@ if __name__ == '__main__':
     args.append('--no-circular-check')
 
   # Default to ninja on linux, but only if no generator has explicitly been set.
+  # Also default to ninja on mac, but only when not building chrome/ios.
   # . -f / --format has precedence over the env var, no need to check for it
   # . set the env var only if it hasn't been set yet
   # . chromium.gyp_env has been applied to os.environ at this point already
   if sys.platform.startswith('linux') and not os.environ.get('GYP_GENERATORS'):
     os.environ['GYP_GENERATORS'] = 'ninja'
+  elif sys.platform == 'darwin' and not os.environ.get('GYP_GENERATORS') and \
+      not 'OS=ios' in os.environ.get('GYP_DEFINES'):
+    os.environ['GYP_GENERATORS'] = 'ninja'
 
   # If CHROMIUM_GYP_SYNTAX_CHECK is set to 1, it will invoke gyp with --check
   # to enfore syntax checking.

landmine_utils.py

@@ -109,6 +109,6 @@ def builder():
     elif IsLinux():
       return 'ninja'
     elif IsMac():
-      return 'xcode'
+      return 'ninja'
     else:
       assert False, 'Don\'t know what builder we\'re using!'