WebUI: Allow ignoring some HTML imports in polymer_modulizer.

This will enable migrating an HTML file to Polymer3, even
before all of its dependencies have been migrated.

Bug: 1026426
Change-Id: I455858a1f1866a9cab83556239ec075cac7f9ddc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2088504Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: dpapad <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#747137}

tools/polymer/polymer.gni

@@ -62,5 +62,9 @@ template("polymer_modulizer") {
     if (defined(invoker.auto_imports)) {
       args += invoker.auto_imports
     }
+
+    if (defined(invoker.ignore_imports)) {
+      args += [ "--ignore_imports" ] + invoker.ignore_imports
+    }
   }
 }

tools/polymer/polymer.py

@@ -72,6 +72,10 @@ _namespace_rewrites = {}
 # ui/webui/resources/html/cr/ui/focus_outline_manager.html is encountered.
 _auto_imports = {}
 
+# Populated from command line arguments. Specifies a list of HTML imports to
+# ignore when converting HTML imports to JS modules.
+_ignore_imports = []
+
 _chrome_redirects = {
     'chrome://resources/polymer/v1_0/': POLYMER_V1_DIR,
     'chrome://resources/html/': 'ui/webui/resources/html/',
@@ -188,8 +192,12 @@ def _generate_js_imports(html_file):
         imports_end_index = i
 
         # Convert HTML import URL to equivalent JS import URL.
-        dep = Dependency(html_file, match.group(1)).to_js_import(_auto_imports)
-        output.append(dep)
+        dep = Dependency(html_file, match.group(1))
+        js_import = dep.to_js_import(_auto_imports)
+        if dep.html_path_normalized in _ignore_imports:
+          output.append('// ' + js_import)
+        else:
+          output.append(js_import)
 
       elif imports_found:
         if re.search(r'^\s*</?if', line):
@@ -469,6 +477,7 @@ def main(argv):
   parser.add_argument('--js_file', required=True)
   parser.add_argument('--html_file', required=True)
   parser.add_argument('--namespace_rewrites', required=False, nargs="*")
+  parser.add_argument('--ignore_imports', required=False, nargs="*")
   parser.add_argument('--auto_imports', required=False, nargs="*")
   parser.add_argument(
       '--html_type', choices=['dom-module', 'style-module', 'custom-style',
@@ -488,6 +497,10 @@ def main(argv):
       path, imports = entry.split('|')
       _auto_imports[path] = imports.split(',')
 
+  # Extract ignored imports from arguments.
+  if args.ignore_imports:
+    global _ignore_imports
+    _ignore_imports = args.ignore_imports
 
   in_folder = os.path.normpath(os.path.join(_CWD, args.in_folder))
   out_folder = os.path.normpath(os.path.join(_CWD, args.out_folder))

tools/polymer/polymer_test.py

@@ -37,6 +37,8 @@ class PolymerModulizerTest(unittest.TestCase):
       '--html_type',  html_type,
       '--namespace_rewrites',
       'Polymer.PaperRippleBehavior|PaperRippleBehavior',
+      '--ignore_imports',
+      'ui/webui/resources/html/ignore_me.html',
       '--auto_imports',
       'ui/webui/resources/html/polymer.html|Polymer,html',
       'third_party/polymer/v1_0/components-chromium/paper-behaviors/paper-ripple-behavior.html|PaperRippleBehavior',

tools/polymer/tests/dom_module.html

 <link rel="import" href="../../../ui/webui/resources/html/polymer.html">
 
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-behaviors/paper-ripple-behavior.html">
+<link rel="import" href="chrome://resources/html/ignore_me.html">
 <link rel="import" href="../shared_vars_css.html">
 <link rel="import" href="foo.html">
 

tools/polymer/tests/dom_module_expected.js

 import {Polymer, html} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
 
 import {PaperRippleBehavior} from 'chrome://resources/polymer/v3_0/paper-behaviors/paper-ripple-behavior.js';
+// import 'chrome://resources/js/ignore_me.m.js';
 import '../shared_vars_css.m.js';
 import './foo.m.js';
 

tools/polymer/tests/dom_module_iife_expected.js

 import {Polymer, html} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
 
 import {PaperRippleBehavior} from 'chrome://resources/polymer/v3_0/paper-behaviors/paper-ripple-behavior.js';
+// import 'chrome://resources/js/ignore_me.m.js';
 import '../shared_vars_css.m.js';
 import './foo.m.js';
 

tools/polymer/tests/dom_module_with_define_expected.js

 import {Polymer, html} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
 
 import {PaperRippleBehavior} from 'chrome://resources/polymer/v3_0/paper-behaviors/paper-ripple-behavior.js';
+// import 'chrome://resources/js/ignore_me.m.js';
 import '../shared_vars_css.m.js';
 import './foo.m.js';