Add GN template for android_assets(). Use it in content_shell_apk.

build/android/gyp/apkbuilder.py

Index: build/android/gyp/apkbuilder.py
diff --git a/build/android/gyp/apkbuilder.py b/build/android/gyp/apkbuilder.py
index 1410d190540ffd51ed25b6b06cd7415fe76b9335..149f218f818c53a0e43cf38bedb56f886b058753 100755
--- a/build/android/gyp/apkbuilder.py
+++ b/build/android/gyp/apkbuilder.py
@@ -18,6 +18,8 @@ from util import build_utils
 def _ParseArgs(args):
   parser = argparse.ArgumentParser()
   build_utils.AddDepfileOption(parser)
+  parser.add_argument('--assets-build-config',
+                      help='Path to .build_config containing the asset list.')
   parser.add_argument('--resource-apk',
                       help='An .ap_ file built using aapt',
                       required=True)
@@ -51,14 +53,22 @@ def main(args):
   args = build_utils.ExpandFileArgs(args)
   options = _ParseArgs(args)
 
+  assets_json = []
+  if options.assets_build_config:
+    assets_json = build_utils.ReadJson(options.assets_build_config)
+    assets_json = assets_json['merged_assets']
+
   native_libs = []
   if options.native_libs_dir:
     native_libs = _ListSubPaths(options.native_libs_dir)
 
-  input_paths = [options.resource_apk] + native_libs
+  input_paths = [options.resource_apk, __file__] + native_libs
   if options.dex_file:
     input_paths.append(options.dex_file)
 
+  for asset_entry in assets_json:
+    input_paths.extend(asset_entry['paths'])
+
   def on_stale_md5():
     tmp_apk = options.output_apk + '.tmp'
     try:
@@ -69,6 +79,19 @@ def main(args):
       # with finalize_apk(), which sometimes aligns and uncompresses the
       # native libraries.
       with zipfile.ZipFile(tmp_apk, 'a', zipfile.ZIP_DEFLATED) as apk:
+        for asset_entry in assets_json:
+          compress_type = zipfile.ZIP_STORED
+          if asset_entry['enable_compression']:
+            compress_type = zipfile.ZIP_DEFLATED
+          for path in asset_entry['paths']:
+            apk_path = 'assets/' + os.path.basename(path)
+            try:
+              apk.getinfo(apk_path)
+              # TODO(agrieve): Add support for asset clobbering if needed.
+              raise Exception('Multiple targets specified the asset path: %s' %
+                              apk_path)
+            except KeyError:
+              apk.write(path, apk_path, compress_type)
         for path in native_libs:
           basename = os.path.basename(path)
           apk.write(path, 'lib/%s/%s' % (options.android_abi, basename))