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-libchromiumcontent.py

@@ -6,13 +6,29 @@ import sys
 
 from lib.config import enable_verbose_mode, get_target_arch
 from lib.util import execute_stdout
+from bootstrap import get_libchromiumcontent_commit 
 
 
 SOURCE_ROOT = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))
+LIBCC_DIR = os.path.join(SOURCE_ROOT, 'vendor', 'libchromiumcontent')
+GCLIENT_DONE_MARKER = os.path.join(SOURCE_ROOT, '.gclient_done')
+LIBCC_COMMIT = get_libchromiumcontent_commit()
+
+
+def update_gclient_done_marker():
+  with open(GCLIENT_DONE_MARKER, 'wb') as f:
+    f.write(LIBCC_COMMIT)
+
+
+def libchromiumcontent_outdated():
+  if not os.path.exists(GCLIENT_DONE_MARKER):
+    return True
+  with open(GCLIENT_DONE_MARKER, 'rb') as f:
+    return f.read() != LIBCC_COMMIT
 
 
 def main():
-  os.chdir(SOURCE_ROOT)
+  os.chdir(LIBCC_DIR)
 
   args = parse_args()
   if args.verbose:
@@ -22,18 +38,25 @@ def main():
   # ./script/update -t x64 --defines=''
   # ./script/build --no_shared_library -t x64
   # ./script/create-dist -c static_library -t x64 --no_zip
-  script_dir = os.path.join(SOURCE_ROOT, 'vendor', 'libchromiumcontent',
-                            'script')
+  script_dir = os.path.join(LIBCC_DIR, 'script')
   bootstrap = os.path.join(script_dir, 'bootstrap')
   update = os.path.join(script_dir, 'update')
   build = os.path.join(script_dir, 'build')
   create_dist = os.path.join(script_dir, 'create-dist')
-  execute_stdout([sys.executable, bootstrap])
-  execute_stdout([sys.executable, update, '-t', args.target_arch,
-                  '--defines', args.defines])
-  execute_stdout([sys.executable, build, '-R', '-t', args.target_arch])
-  execute_stdout([sys.executable, create_dist, '-c', 'static_library',
-                  '--no_zip', '-t', args.target_arch])
+  if args.force_update or libchromiumcontent_outdated():
+    execute_stdout([sys.executable, bootstrap])
+    execute_stdout([sys.executable, update, '-t', args.target_arch,
+                    '--defines', args.defines])
+    update_gclient_done_marker()
+  if args.debug:
+    execute_stdout([sys.executable, build, '-D', '-t', args.target_arch])
+    execute_stdout([sys.executable, create_dist, '-c', 'shared_library',
+                    '--no_zip', '--keep-debug-symbols',
+                    '-t', args.target_arch])
+  else:
+    execute_stdout([sys.executable, build, '-R', '-t', args.target_arch])
+    execute_stdout([sys.executable, create_dist, '-c', 'static_library',
+                    '--no_zip', '-t', args.target_arch])
 
 
 def parse_args():
@@ -44,6 +67,10 @@ def parse_args():
                       help='The definetions passed to gyp')
   parser.add_argument('-v', '--verbose', action='store_true',
                       help='Prints the output of the subprocesses')
+  parser.add_argument('-d', '--debug', action='store_true',
+                      help='Build libchromiumcontent for debugging')
+  parser.add_argument('--force-update', default=False, action='store_true',
+                      help='Force gclient to update libchromiumcontent')
   return parser.parse_args()