Make optimize_webui work for non-default toolchain

This CL makes the optimize_webui work with non-default toolchain by
avoiding assuming that the gen directory will always be out/gen.

Bug: 1129223
Change-Id: I575474c2ef983008979329706a029115fe34c9c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2419717
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Cr-Commit-Position: refs/heads/master@{#814032}

chrome/browser/resources/optimize_webui.gni

@@ -57,6 +57,8 @@ template("optimize_webui") {
       rebase_path(target_gen_dir, root_build_dir),
       "--depfile",
       rebase_path(depfile, root_build_dir),
+      "--gen_dir_relpath",
+      rebase_path(root_gen_dir, root_build_dir),
     ]
 
     args += [ "--js_out_files" ] + invoker.js_out_files

chrome/browser/resources/optimize_webui.py

@@ -165,7 +165,7 @@ def _update_dep_file(in_folder, args, manifest):
 # pass it information about the location of the directories and files to exclude
 # from the bundle.
 def _generate_rollup_config(tmp_out_dir, path_to_plugin, in_path, host,
-                            excludes):
+                            excludes, gen_dir_relpath):
   rollup_config_file = os.path.join(tmp_out_dir, 'rollup.config.js')
   excludes_string = '[\'' + '\', \''.join(excludes) + '\']'
   with open(rollup_config_file, 'w') as f:
@@ -174,7 +174,7 @@ def _generate_rollup_config(tmp_out_dir, path_to_plugin, in_path, host,
     f.write('export default({\n')
     f.write('  plugins: [ plugin(\'%s\', \'%s\', \'%s\', \'%s\', %s) ]\n' % (
         _SRC_PATH.replace('\\', '/'),
-        os.path.join(_CWD, 'gen').replace('\\', '/'),
+        os.path.join(_CWD, gen_dir_relpath).replace('\\', '/'),
         in_path.replace('\\', '/'), host, excludes_string))
     f.write('});')
     f.close()
@@ -213,7 +213,8 @@ def _bundle_v3(tmp_out_dir, in_path, out_path, manifest_out_path, args,
   path_to_plugin = os.path.join(
       os.path.abspath(_HERE_PATH), 'tools', 'rollup_plugin.js')
   rollup_config_file = _generate_rollup_config(tmp_out_dir, path_to_plugin,
-                                               in_path, args.host, excludes)
+                                               in_path, args.host, excludes,
+                                               args.gen_dir_relpath)
   rollup_args = [os.path.join(in_path, f) for f in args.js_module_in_files]
 
   # Confirm names are as expected. This is necessary to avoid having to replace
@@ -379,6 +380,9 @@ def main(argv):
   parser.add_argument('--js_out_files', nargs='*', required=True)
   parser.add_argument('--out_folder', required=True)
   parser.add_argument('--js_module_in_files', nargs='*')
+  parser.add_argument('--gen_dir_relpath', default='gen', help='Path of the '
+      'gen directory relative to the out/. If running in the default '
+      'toolchain, the path is gen, otherwise $toolchain_name/gen')
   args = parser.parse_args(argv)
 
   # Either JS module input files (for Polymer 3) or HTML input and output files

chrome/browser/resources/optimize_webui_test.py

@@ -81,13 +81,13 @@ import './element_in_dir/element_in_dir.js';
 <script type="module" src="ui.js"></script>
 ''')
 
-  def _write_v3_files_with_resources_to_src_dir(self):
+  def _write_v3_files_with_resources_to_src_dir(self, gen_dir='gen'):
     resources_path = os.path.join(
-        _HERE_DIR.replace('\\', '/'), 'gen', 'ui', 'webui', 'resources',
+        _HERE_DIR.replace('\\', '/'), gen_dir, 'ui', 'webui', 'resources',
         'preprocessed', 'js', 'fake_resource.js')
     os.makedirs(os.path.dirname(resources_path))
 
-    self._tmp_dirs.append('gen')
+    self._tmp_dirs.append(gen_dir)
     with open(resources_path, 'w') as tmp_file:
       tmp_file.write("alert('hello from shared resource');")
 
@@ -179,6 +179,24 @@ import './element_in_dir/element_in_dir.js';
             '../gen/ui/webui/resources/preprocessed/js/fake_resource.js'),
         depfile_d)
 
+  def testV3OptimizeWithResourcesInNonDefaultToolchain(self):
+    self._write_v3_files_with_resources_to_src_dir(gen_dir='ash_clang_64/gen')
+    args = [
+      '--js_module_in_files', 'ui.js',
+      '--js_out_files', 'ui.rollup.js',
+      '--gen_dir_relpath', 'ash_clang_64/gen',
+    ]
+    self._run_optimize(args)
+
+    ui_rollup_js = self._read_out_file('ui.rollup.js')
+    self.assertIn('hello from shared resource', ui_rollup_js)
+
+    depfile_d = self._read_out_file('depfile.d')
+    self.assertIn(
+        os.path.normpath(
+            '../ash_clang_64/gen/ui/webui/resources/preprocessed/js/'
+            'fake_resource.js'), depfile_d)
+
   def testV3MultiBundleOptimize(self):
     self._write_v3_files_to_src_dir()
     self._write_file_to_src_dir('lazy_element.js',