Improve development workflow with built libchromiumcontent

- Add `--debug_libchromiumcontent` to build libchromiumcontent for debugging
  (shared library build).
- By default, only invoke `gclient sync` the first time to checkout chromium
  source tree. Add `--force_update_libchromiumcontent` switch to force updating.
- Document new options.

The goal is to allow faster edit/compile cycles when debugging/making changes
to libchromiumcontent.

script/build.py

@@ -11,6 +11,9 @@ from lib.util import electron_gyp, import_vs_env
 
 CONFIGURATIONS = ['Release', 'Debug']
 SOURCE_ROOT = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))
+LIBCC_SOURCE_ROOT = os.path.join(SOURCE_ROOT, 'vendor', 'libchromiumcontent')
+LIBCC_DIST_MAIN = os.path.join(LIBCC_SOURCE_ROOT, 'dist', 'main')
+GCLIENT_DONE = os.path.join(SOURCE_ROOT, '.gclient_done')
 
 
 def main():
@@ -24,6 +27,19 @@ def main():
     ninja += '.exe'
 
   args = parse_args()
+  if args.libcc:
+    if ('D' not in args.configuration
+        or not os.path.exists(GCLIENT_DONE)
+        or not os.path.exists(os.path.join(LIBCC_DIST_MAIN, 'build.ninja'))):
+      sys.stderr.write('--libcc should only be used when '
+                       'libchromiumcontent was built with bootstrap.py -d '
+                       '--debug_libchromiumcontent' + os.linesep)
+      sys.exit(1)
+    script = os.path.join(LIBCC_SOURCE_ROOT, 'script', 'build')
+    subprocess.check_call([sys.executable, script, '-D', '-t',
+                           get_target_arch()])
+    subprocess.check_call([ninja, '-C', LIBCC_DIST_MAIN])
+
   for config in args.configuration:
     build_path = os.path.join('out', config[0])
     ret = subprocess.call([ninja, '-C', build_path, args.target])
@@ -42,6 +58,13 @@ def parse_args():
                       help='Build specified target',
                       default=electron_gyp()['project_name%'],
                       required=False)
+  parser.add_argument('--libcc',
+                      help=(
+                        'Build libchromiumcontent first. Should be used only '
+                        'when libchromiumcontent as built with boostrap.py '
+                        '-d --debug_libchromiumcontent.'
+                      ),
+                      action='store_true', default=False)
   return parser.parse_args()