WUG (Web UI generator) is an utility toolkit which

facilitates WebUI creation.

All parts of WUG are implemented:
* Base classes for view (View) and view-model (ViewModel)
* WebUIView -- specialization of View for use in WebUI.
* View's CC, HTML and JS code generator
* Templates for GYP and GN which help to generate code and
  produce components from generated code.

Tests to follow.

TEST=none
TBR=avi@chromium.org,mark@chromium.org
BUG=459230

Review URL: https://codereview.chromium.org/928163002

Cr-Commit-Position: refs/heads/master@{#318884}

26 files changed, 2383 insertions, 0 deletions

diff --git a/components/webui_generator/BUILD.gn b/components/webui_generator/BUILD.gn
new file mode 100644
index 0000000..13e167f
--- /dev/null
+++ b/components/webui_generator/BUILD.gn
@@ -0,0 +1,36 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# GYP version: components/webui_generator.gypi:webui_generator
+component("webui_generator") {
+  sources = [
+    "data_source_util.cc",
+    "data_source_util.h",
+    "export.h",
+    "view.cc",
+    "view.h",
+    "view_model.cc",
+    "view_model.h",
+    "web_ui_view.cc",
+    "web_ui_view.h",
+  ]
+
+  defines = [ "WUG_IMPLEMENTATION" ]
+
+  deps = [
+    "//components/resources",
+    "//ui/base",
+  ]
+
+  public_deps = [
+    "//base",
+    "//components/login",
+    "//content/public/browser",
+  ]
+}
+
+# Config for users of generated files.
+config("wug_generated_config") {
+  include_dirs = [ "$root_gen_dir/wug" ]
+}
diff --git a/components/webui_generator/DEPS b/components/webui_generator/DEPS
new file mode 100644
index 0000000..3985eef
--- /dev/null
+++ b/components/webui_generator/DEPS
@@ -0,0 +1,6 @@
+include_rules = [
+  "+base",
+  "+content/public/browser",
+  "+grit/components_resources.h",
+  "+components/login",
+]
diff --git a/components/webui_generator/OWNERS b/components/webui_generator/OWNERS
new file mode 100644
index 0000000..df660f7
--- /dev/null
+++ b/components/webui_generator/OWNERS
@@ -0,0 +1 @@
+dzhioev@chromium.org
diff --git a/components/webui_generator/data_source_util.cc b/components/webui_generator/data_source_util.cc
new file mode 100644
index 0000000..a3103cd
--- /dev/null
+++ b/components/webui_generator/data_source_util.cc
@@ -0,0 +1,22 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/webui_generator/data_source_util.h"
+#include "content/public/browser/web_ui_data_source.h"
+#include "grit/components_resources.h"
+
+namespace webui_generator {
+
+void SetUpDataSource(content::WebUIDataSource* data_source) {
+  data_source->AddResourcePath("webui_generator/webui-view.html",
+                               IDR_WUG_WEBUI_VIEW_HTML);
+  data_source->AddResourcePath("webui_generator/webui-view.js",
+                               IDR_WUG_WEBUI_VIEW_JS);
+  data_source->AddResourcePath("webui_generator/context.js",
+                               IDR_WUG_CONTEXT_JS);
+  data_source->AddResourcePath("webui_generator/context.html",
+                               IDR_WUG_CONTEXT_HTML);
+}
+
+}  // namespace webui_generator
diff --git a/components/webui_generator/data_source_util.h b/components/webui_generator/data_source_util.h
new file mode 100644
index 0000000..95abe42
--- /dev/null
+++ b/components/webui_generator/data_source_util.h
@@ -0,0 +1,21 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_WUG_DATA_SOURCE_UTIL_H_
+#define CHROME_BROWSER_UI_WEBUI_WUG_DATA_SOURCE_UTIL_H_
+
+#include "components/webui_generator/export.h"
+
+namespace content {
+class WebUIDataSource;
+}
+
+namespace webui_generator {
+
+// Adds common resources needed for WUG to |data_source|.
+void WUG_EXPORT SetUpDataSource(content::WebUIDataSource* data_source);
+
+}  // namespace webui_generator
+
+#endif  // CHROME_BROWSER_UI_WEBUI_WUG_DATA_SOURCE_UTIL_H_
diff --git a/components/webui_generator/export.h b/components/webui_generator/export.h
new file mode 100644
index 0000000..226cfd2
--- /dev/null
+++ b/components/webui_generator/export.h
@@ -0,0 +1,34 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_WUG_EXPORT_H_
+#define COMPONENTS_WUG_EXPORT_H_
+
+#if defined(COMPONENT_BUILD)
+
+#if defined(WIN32)
+
+#if defined(WUG_IMPLEMENTATION)
+#define WUG_EXPORT __declspec(dllexport)
+#else
+#define WUG_EXPORT __declspec(dllimport)
+#endif  // defined(WUG_IMPLEMENTATION)
+
+#else  // defined(WIN32)
+
+#if defined(WUG_IMPLEMENTATION)
+#define WUG_EXPORT __attribute__((visibility("default")))
+#else
+#define WUG_EXPORT
+#endif  // defined(WUG_IMPLEMENTATION)
+
+#endif  // defined(WIN32)
+
+#else  // defined(COMPONENT_BUILD)
+
+#define WUG_EXPORT
+
+#endif
+
+#endif  // COMPONENTS_WUG_EXPORT_H_
diff --git a/components/webui_generator/generator/build_helper.py b/components/webui_generator/generator/build_helper.py
new file mode 100644
index 0000000..06232e6
--- /dev/null
+++ b/components/webui_generator/generator/build_helper.py
@@ -0,0 +1,69 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Provides various information needed for GYP and GN to generate and build
+# files.
+
+import os
+import sys
+
+from declaration import Declaration
+import export_h
+import util
+import view_model
+import web_ui_view
+
+def GetImportDependencies(declaration):
+  return set(child.build_target for child in declaration.children.itervalues())
+
+parser = util.CreateArgumentParser()
+parser.add_argument('--output',
+                    choices=['view_cc', 'view_h', 'model_cc', 'model_h',
+                             'export_h', 'dirname', 'target_name', 'imports',
+                             'impl_macro', 'import_dependencies',
+                             'list_outputs'],
+                    required=True,
+                    help='Type of output')
+parser.add_argument('--gn', action='store_true',
+                    help='Is called by GN')
+args = parser.parse_args()
+declaration_path = os.path.relpath(args.declaration, args.root)
+os.chdir(args.root)
+try:
+  declaration = Declaration(declaration_path)
+except Exception as e:
+  print >> sys.stderr, e.message
+  sys.exit(1)
+
+if args.output == 'view_cc':
+  print declaration.webui_view_cc_name
+elif args.output == 'view_h':
+  print declaration.webui_view_h_name
+elif args.output == 'model_cc':
+  print declaration.view_model_cc_name
+elif args.output == 'model_h':
+  print declaration.view_model_h_name
+elif args.output == 'export_h':
+  print declaration.export_h_name
+elif args.output == 'dirname':
+  print os.path.dirname(declaration_path)
+elif args.output == 'target_name':
+  print declaration.build_target
+elif args.output == 'imports':
+  for i in declaration.imports:
+    print '//' + i
+elif args.output == 'import_dependencies':
+  for d in GetImportDependencies(declaration):
+    print (':' if args.gn else '') + d
+elif args.output == 'list_outputs':
+  outputs = web_ui_view.ListOutputs(declaration, args.destination) + \
+            view_model.ListOutputs(declaration, args.destination) + \
+            export_h.ListOutputs(declaration, args.destination)
+  for output in outputs:
+    print output
+elif args.output == 'impl_macro':
+  print declaration.component_impl_macro
+else:
+  assert False
+
diff --git a/components/webui_generator/generator/declaration.py b/components/webui_generator/generator/declaration.py
new file mode 100644
index 0000000..e9863b5
--- /dev/null
+++ b/components/webui_generator/generator/declaration.py
@@ -0,0 +1,312 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import itertools
+import json
+import os.path
+import re
+
+import util
+
+# Schema is described as follows:
+# * for simple type:
+#     %simple_type%
+# * for list:
+#     (list, %items_schema%)
+# * for dict:
+#     (dict, { '%key_name%': (%is_key_required%, %value_schema%),
+#            ...
+#            })
+DECLARATION_SCHEMA = (dict, {
+  'imports': (False, (list, unicode)),
+  'type': (True, unicode),
+  'children': (False, (list, (dict, {
+                'id': (True, unicode),
+                'type': (True, unicode),
+                'comment': (False, unicode)
+              }))),
+  'context': (False, (list, (dict, {
+               'name': (True, unicode),
+               'type': (False, unicode),
+               'default': (False, object),
+               'comment': (False, unicode)
+             }))),
+  'events': (False, (list, (dict, {
+              'name': (True, unicode),
+              'comment': (False, unicode)
+            }))),
+  'strings': (False, (list, (dict, {
+               'name': (True, unicode),
+               'comment': (False, unicode)
+             }))),
+  'comment': (False, unicode)
+})
+
+# Returns (True,) if |obj| matches |schema|.
+# Otherwise returns (False, msg), where |msg| is a diagnostic message.
+def MatchSchema(obj, schema):
+  expected_type = schema[0] if isinstance(schema, tuple) else schema
+  if not isinstance(obj, expected_type):
+    return (False, 'Wrong type, expected %s, got %s.' %
+                       (expected_type, type(obj)))
+  if expected_type == dict:
+    obj_keys = set(obj.iterkeys())
+    allowed_keys = set(schema[1].iterkeys())
+    required_keys = set(kv[0] for kv in schema[1].iteritems() if kv[1][0])
+    if not obj_keys.issuperset(required_keys):
+      missing_keys = required_keys.difference(obj_keys)
+      return (False, 'Missing required key%s %s.' %
+                ('s' if len(missing_keys) > 1 else '',
+                 ', '.join('\'%s\'' % k for k in missing_keys)))
+    if not obj_keys.issubset(allowed_keys):
+      unknown_keys = obj_keys.difference(allowed_keys)
+      return (False, 'Unknown key%s %s.' %
+                ('s' if len(unknown_keys) > 1 else '',
+                 ', '.join('\'%s\'' % k for k in unknown_keys)))
+    for key in obj:
+      match = MatchSchema(obj[key], schema[1][key][1])
+      if not match[0]:
+        return (False, ('[\'%s\'] ' % key) + match[1])
+  elif expected_type == list:
+    for i, item in enumerate(obj):
+      match = MatchSchema(item, schema[1])
+      if not match[0]:
+        return (False, ('[%d] ' % i) + match[1])
+  return (True,)
+
+def CheckDeclarationIsValid(declaration):
+  match = MatchSchema(declaration, DECLARATION_SCHEMA)
+  if not match[0]:
+    raise Exception('Declaration is not valid: ' + match[1])
+
+def CheckFieldIsUnique(list_of_dicts, field):
+  seen = {}
+  for i, d in enumerate(list_of_dicts):
+    value = d[field]
+    if value in seen:
+      raise Exception(
+          '[%d] Object with "%s" equal to "%s" already exists. See [%d].' %
+              (i, field, value, seen[value]))
+    else:
+      seen[value] = i
+
+class FieldDeclaration(object):
+  ALLOWED_TYPES = [
+    'boolean',
+    'integer',
+    'double',
+    'string',
+    'string_list'
+  ]
+
+  DEFAULTS = {
+    'boolean': False,
+    'integer': 0,
+    'double': 0.0,
+    'string': u'',
+    'string_list': []
+  }
+
+  def __init__(self, declaration):
+    self.name = declaration['name']
+    self.id = util.ToLowerCamelCase(self.name)
+    self.type = declaration['type'] if 'type' in declaration else 'string'
+    if self.type not in self.ALLOWED_TYPES:
+      raise Exception('Unknown type of context field "%s": "%s"' %
+                      (self.name, self.type))
+    self.default_value = declaration['default'] if 'default' in declaration \
+            else self.DEFAULTS[self.type]
+    if type(self.default_value) != type(self.DEFAULTS[self.type]):
+      raise Exception('Wrong type of default for field "%s": '
+                      'expected "%s", got "%s"' %
+                          (self.name,
+                           type(self.DEFAULTS[self.type]),
+                           type(self.default_value)))
+
+class Declaration(object):
+  class InvalidDeclaration(Exception):
+    def __init__(self, path, message):
+      super(Exception, self).__init__(
+          'Invalid declaration file "%s": %s' % (path, message))
+
+  class DeclarationsStorage(object):
+    def __init__(self):
+      self.by_path = {}
+      self.by_type = {}
+
+    def Add(self, declaration):
+      assert declaration.path not in self.by_path
+      self.by_path[declaration.path] = declaration
+      if declaration.type in self.by_type:
+        raise Exception(
+            'Redefinition of type "%s". ' \
+            'Previous definition was in "%s".' % \
+                (declaration.type, self.by_type[declaration.type].path))
+      self.by_type[declaration.type] = declaration
+
+    def HasPath(self, path):
+      return path in self.by_path
+
+    def HasType(self, type):
+      return type in self.by_type
+
+    def GetByPath(self, path):
+      return self.by_path[path]
+
+    def GetByType(self, type):
+      return self.by_type[type]
+
+    def GetKnownPathes(self):
+      return self.by_path.keys()
+
+
+  def __init__(self, path, known_declarations=None):
+    if known_declarations is None:
+      known_declarations = Declaration.DeclarationsStorage()
+    self.path = path
+    try:
+      self.data = json.load(open(path, 'r'))
+      CheckDeclarationIsValid(self.data)
+      filename_wo_ext = os.path.splitext(os.path.basename(self.path))[0]
+      if self.data['type'] != filename_wo_ext:
+        raise Exception(
+          'File with declaration of type "%s" should be named "%s.json"' %
+              (self.data['type'], filename_wo_ext))
+
+      known_declarations.Add(self)
+      if 'imports' in self.data:
+        for import_path in self.data['imports']:
+          #TODO(dzhioev): detect circular dependencies.
+          if not known_declarations.HasPath(import_path):
+            Declaration(import_path, known_declarations)
+
+      for key in ['children', 'strings', 'context', 'events']:
+        if key in self.data:
+          unique_field = 'id' if key == 'children' else 'name'
+          try:
+            CheckFieldIsUnique(self.data[key], unique_field)
+          except Exception as e:
+            raise Exception('["%s"] %s' % (key, e.message))
+        else:
+          self.data[key] = []
+
+      self.children = {}
+      for child_data in self.data['children']:
+        child_type = child_data['type']
+        child_id = child_data['id']
+        if not known_declarations.HasType(child_type):
+          raise Exception('Unknown type "%s" for child "%s"' %
+                              (child_type, child_id))
+        self.children[child_id] = known_declarations.GetByType(child_type)
+
+      self.fields = [FieldDeclaration(d) for d in self.data['context']]
+      fields_names = [field.name for field in self.fields]
+      if len(fields_names) > len(set(fields_names)):
+        raise Exception('Duplicate fields in declaration.')
+      self.known_declarations = known_declarations
+    except Declaration.InvalidDeclaration:
+      raise
+    except Exception as e:
+      raise Declaration.InvalidDeclaration(self.path, e.message)
+
+  @property
+  def type(self):
+    return self.data['type']
+
+  @property
+  def strings(self):
+    return (string['name'] for string in self.data['strings'])
+
+  @property
+  def events(self):
+    return (event['name'] for event in self.data['events'])
+
+  @property
+  def webui_view_basename(self):
+    return self.type + '_web_ui_view'
+
+  @property
+  def webui_view_h_name(self):
+    return self.webui_view_basename + '.h'
+
+  @property
+  def webui_view_cc_name(self):
+    return self.webui_view_basename + '.cc'
+
+  @property
+  def webui_view_include_path(self):
+    return os.path.join(os.path.dirname(self.path), self.webui_view_h_name)
+
+  @property
+  def export_h_name(self):
+    return self.type + '_export.h'
+
+  @property
+  def component_export_macro(self):
+    return "WUG_" + self.type.upper() + "_EXPORT"
+
+  @property
+  def component_impl_macro(self):
+    return "WUG_" + self.type.upper() + "_IMPLEMENTATION"
+
+  @property
+  def export_h_include_path(self):
+    return os.path.join(os.path.dirname(self.path), self.export_h_name)
+
+  @property
+  def view_model_basename(self):
+    return self.type + '_view_model'
+
+  @property
+  def view_model_h_name(self):
+    return self.view_model_basename + '.h'
+
+  @property
+  def view_model_cc_name(self):
+    return self.view_model_basename + '.cc'
+
+  @property
+  def view_model_include_path(self):
+    return os.path.join(os.path.dirname(self.path), self.view_model_h_name)
+
+  @property
+  def html_view_basename(self):
+    return '%s-view' % self.type.replace('_', '-')
+
+  @property
+  def html_view_html_name(self):
+    return self.html_view_basename + '.html'
+
+  @property
+  def html_view_js_name(self):
+    return self.html_view_basename + '.js'
+
+  @property
+  def html_view_html_include_path(self):
+    return os.path.join(os.path.dirname(self.path), self.html_view_html_name)
+
+  @property
+  def html_view_js_include_path(self):
+    return os.path.join(os.path.dirname(self.path), self.html_view_js_name)
+
+  @property
+  def build_target(self):
+    return self.type + "_wug_generated"
+
+  @property
+  def webui_view_class(self):
+    return util.ToUpperCamelCase(self.type) + 'WebUIView'
+
+  @property
+  def view_model_class(self):
+    return util.ToUpperCamelCase(self.type) + 'ViewModel'
+
+  @property
+  def imports(self):
+    res = set(self.known_declarations.GetKnownPathes())
+    res.remove(self.path)
+    return res
+
+
+
diff --git a/components/webui_generator/generator/export_h.py b/components/webui_generator/generator/export_h.py
new file mode 100644
index 0000000..3c4eceb
--- /dev/null
+++ b/components/webui_generator/generator/export_h.py
@@ -0,0 +1,66 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import datetime
+import util
+import os
+
+H_FILE_TEMPLATE = \
+"""// Copyright %(year)d The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// NOTE: this file is generated from "%(source)s". Do not modify directly.
+
+#ifndef %(include_guard)s
+#define %(include_guard)s
+
+#if defined(COMPONENT_BUILD)
+
+#if defined(WIN32)
+
+#if defined(%(impl_macro)s)
+#define %(export_macro)s __declspec(dllexport)
+#else
+#define %(export_macro)s __declspec(dllimport)
+#endif  // defined(%(impl_macro)s)
+
+#else  // defined(WIN32)
+
+#if defined(%(impl_macro)s)
+#define %(export_macro)s __attribute__((visibility("default")))
+#else
+#define %(export_macro)s
+#endif  // defined(%(impl_macro)s)
+
+#endif  // defined(WIN32)
+
+#else  // defined(COMPONENT_BUILD)
+
+#define %(export_macro)s
+
+#endif
+
+#endif  // %(include_guard)s
+"""
+
+def GenHFile(declaration):
+  subs = {}
+  subs['year'] = datetime.date.today().year
+  subs['source'] = declaration.path
+  subs['include_guard'] = util.PathToIncludeGuard(
+                              declaration.export_h_include_path)
+  subs['export_macro'] = declaration.component_export_macro
+  subs['impl_macro'] = declaration.component_impl_macro
+  return H_FILE_TEMPLATE % subs
+
+def ListOutputs(declaration, destination):
+  dirname = os.path.join(destination, os.path.dirname(declaration.path))
+  h_file_path = os.path.join(dirname, declaration.export_h_name)
+  return [h_file_path]
+
+def Gen(declaration, destination):
+  h_file_path = ListOutputs(declaration, destination)[0]
+  util.CreateDirIfNotExists(os.path.dirname(h_file_path))
+  open(h_file_path, 'w').write(GenHFile(declaration))
diff --git a/components/webui_generator/generator/gen_sources.py b/components/webui_generator/generator/gen_sources.py
new file mode 100644
index 0000000..6b9a87a
--- /dev/null
+++ b/components/webui_generator/generator/gen_sources.py
@@ -0,0 +1,27 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import os.path
+import sys
+
+from declaration import Declaration
+import export_h
+import util
+import view_model
+import web_ui_view
+
+args = util.CreateArgumentParser().parse_args()
+declaration_path = os.path.relpath(args.declaration, args.root)
+destination = os.path.relpath(args.destination, args.root)
+os.chdir(args.root)
+try:
+  declaration = Declaration(declaration_path)
+except Exception as e:
+  print >> sys.stderr, e.message
+  sys.exit(1)
+view_model.Gen(declaration, destination)
+web_ui_view.Gen(declaration, destination)
+export_h.Gen(declaration, destination)
+
diff --git a/components/webui_generator/generator/html_view.py b/components/webui_generator/generator/html_view.py
new file mode 100644
index 0000000..73fc8a9
--- /dev/null
+++ b/components/webui_generator/generator/html_view.py
@@ -0,0 +1,111 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import util
+import os
+import datetime
+
+HTML_FILE_TEMPLATE = \
+"""<!-- Copyright %(year)d The Chromium Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style license that can be
+     found in the LICENSE file. -->
+
+<!-- NOTE: this file is generated from "%(source)s". Do not modify directly. -->
+
+<!doctype html>
+<html><head>
+<link rel="import" href="chrome://resources/polymer/polymer/polymer.html">
+<link rel="import" href="/webui_generator/webui-view.html">
+%(children_includes)s
+</head><body>
+<polymer-element name="%(element_name)s" extends="webui-view">
+</polymer-element>
+<script src="%(js_file_path)s"></script>
+</body></html>
+"""
+
+JS_FILE_TEMPLATE = \
+"""// Copyright %(year)d The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// NOTE: this file is generated from "%(source)s". Do not modify directly.
+
+
+Polymer('%(element_name)s', (function() {
+  'use strict';
+  return {
+  getType: function() {
+    return '%(type)s';
+  },
+
+  initialize: function() {},
+  contextChanged: function(changedKeys) {},
+
+  initChildren_: function() {
+%(init_children_body)s
+  },
+
+  initContext_: function() {
+%(init_context_body)s
+  }
+  }
+})());
+"""
+
+def GetCommonSubistitutions(declaration):
+  subs = {}
+  subs['year'] = datetime.date.today().year
+  subs['element_name'] = declaration.type.replace('_', '-') + '-view'
+  subs['source'] = declaration.path
+  return subs
+
+def GenChildrenIncludes(children):
+  lines = []
+  for declaration in set(children.itervalues()):
+    lines.append('<link rel="import" href="/%s">' %
+                     declaration.html_view_html_include_path)
+  return '\n'.join(lines)
+
+def GenHTMLFile(declaration):
+  subs = GetCommonSubistitutions(declaration)
+  subs['js_file_path'] = subs['element_name'] + '.js'
+  subs['children_includes'] = GenChildrenIncludes(declaration.children)
+  return HTML_FILE_TEMPLATE % subs
+
+def GenInitChildrenBody(children):
+  lines = []
+  lines.append('    var child = null;');
+  for id in children:
+    lines.append('    child = this.shadowRoot.querySelector(\'[wugid="%s"]\');'
+                     % id);
+    lines.append('    if (!child)');
+    lines.append('      console.error(this.path_ + \'$%s not found.\');' % id);
+    lines.append('    else');
+    lines.append('      child.setPath_(this.path_ + \'$%s\');' % id)
+  return '\n'.join(lines)
+
+def GenInitContextBody(fields):
+  lines = []
+  for field in fields:
+    value = ''
+    if field.type in ['integer', 'double']:
+      value = str(field.default_value)
+    elif field.type == 'boolean':
+      value = 'true' if field.default_value else 'false'
+    elif field.type == 'string':
+      value = '\'%s\'' % field.default_value
+    elif field.type == 'string_list':
+      value = '[' + \
+        ', '.join('\'%s\'' % s for s in field.default_value) + ']'
+    lines.append('    this.context.set(\'%s\', %s);' % (field.id, value))
+  lines.append('    this.context.getChangesAndReset();')
+  return '\n'.join(lines)
+
+def GenJSFile(declaration):
+  subs = GetCommonSubistitutions(declaration)
+  subs['type'] = declaration.type
+  subs['init_children_body'] = GenInitChildrenBody(declaration.children)
+  subs['init_context_body'] = GenInitContextBody(declaration.fields)
+  return JS_FILE_TEMPLATE % subs
diff --git a/components/webui_generator/generator/util.py b/components/webui_generator/generator/util.py
new file mode 100644
index 0000000..28a20db
--- /dev/null
+++ b/components/webui_generator/generator/util.py
@@ -0,0 +1,30 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import argparse
+import os.path
+import re
+
+def CreateArgumentParser():
+  parser = argparse.ArgumentParser()
+  parser.add_argument('declaration', help='Path to declaration file.')
+  parser.add_argument('--root', default='.', help='Path to src/ dir.')
+  parser.add_argument('--destination',
+                      help='Root directory for generated files.')
+  return parser
+
+def ToUpperCamelCase(underscore_name):
+  return re.sub(r'(?:_|^)(.)', lambda m: m.group(1).upper(), underscore_name)
+
+def ToLowerCamelCase(underscore_name):
+  return re.sub(r'_(.)', lambda m: m.group(1).upper(), underscore_name)
+
+def PathToIncludeGuard(path):
+  return re.sub(r'[/.]', '_', path.upper()) + '_'
+
+def CreateDirIfNotExists(path):
+  if not os.path.isdir(path):
+    if os.path.exists(path):
+      raise Exception('%s exists and is not a directory.' % path)
+    os.makedirs(path)
diff --git a/components/webui_generator/generator/view_model.py b/components/webui_generator/generator/view_model.py
new file mode 100644
index 0000000..a920807
--- /dev/null
+++ b/components/webui_generator/generator/view_model.py
@@ -0,0 +1,329 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import datetime
+import util
+
+H_FILE_TEMPLATE = \
+"""// Copyright %(year)d The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// NOTE: this file is generated from "%(source)s". Do not modify directly.
+
+#ifndef %(include_guard)s
+#define %(include_guard)s
+
+#include "base/macros.h"
+#include "components/webui_generator/view_model.h"
+#include "%(export_h_include_path)s"
+
+namespace content {
+class BrowserContext;
+}
+
+%(children_forward_declarations)s
+
+namespace gen {
+
+class %(export_macro)s %(class_name)s : public ::webui_generator::ViewModel {
+ public:
+  using FactoryFunction = %(class_name)s* (*)(content::BrowserContext*);
+
+%(context_keys)s
+
+  static %(class_name)s* Create(content::BrowserContext* context);
+  static void SetFactory(FactoryFunction factory);
+
+  %(class_name)s();
+
+%(children_getters)s
+
+%(context_getters)s
+
+%(event_handlers)s
+
+ void Initialize() override {}
+ void OnAfterChildrenReady() override {}
+ void OnViewBound() override {}
+
+ private:
+  void OnEvent(const std::string& event) final;
+
+  static FactoryFunction factory_function_;
+};
+
+}  // namespace gen
+
+#endif  // %(include_guard)s
+"""
+
+CHILD_FORWARD_DECLARATION_TEMPLATE = \
+"""namespace gen {
+  class %(child_type)s;
+}
+"""
+CONTEXT_KEY_DECLARATION_TEMPLATE = \
+"""  static const char %s[];"""
+
+CHILD_GETTER_DECLARATION_TEMPLATE = \
+"""  virtual gen::%(child_type)s* %(method_name)s() const;""";
+
+CONTEXT_VALUE_GETTER_DECLARATION_TEMPLATE = \
+"""  %(type)s %(method_name)s() const;"""
+
+EVENT_HANDLER_DECLARATION_TEMPLATE = \
+"""  virtual void %s() = 0;"""
+
+CC_FILE_TEMPLATE = \
+"""// Copyright %(year)d The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// NOTE: this file is generated from "%(source)s". Do not modify directly.
+
+#include "%(header_path)s"
+
+#include "base/logging.h"
+#include "components/webui_generator/view.h"
+%(children_includes)s
+
+namespace gen {
+
+%(context_keys)s
+
+%(class_name)s::FactoryFunction %(class_name)s::factory_function_;
+
+%(class_name)s* %(class_name)s::Create(content::BrowserContext* context) {
+  CHECK(factory_function_) << "Factory function for %(class_name)s was not "
+      "set.";
+  return factory_function_(context);
+}
+
+void %(class_name)s::SetFactory(FactoryFunction factory) {
+  factory_function_ = factory;
+}
+
+%(class_name)s::%(class_name)s() {
+%(constructor_body)s
+}
+
+%(children_getters)s
+
+%(context_getters)s
+
+void %(class_name)s::OnEvent(const std::string& event) {
+%(event_dispatcher_body)s
+  LOG(ERROR) << "Unknown event '" << event << "'";
+}
+
+}  // namespace gen
+"""
+
+CONTEXT_KEY_DEFINITION_TEMPLATE = \
+"""const char %(class_name)s::%(name)s[] = "%(value)s";"""
+
+CHILD_GETTER_DEFINITION_TEMPLATE = \
+"""gen::%(child_type)s* %(class_name)s::%(method_name)s() const {
+  return static_cast<gen::%(child_type)s*>(
+      view()->GetChild("%(child_id)s")->GetViewModel());
+}
+"""
+
+CONTEXT_VALUE_GETTER_DEFINITION_TEMPLATE = \
+"""%(type)s %(class_name)s::%(method_name)s() const {
+    return context().%(context_getter)s(%(key_constant)s);
+}
+"""
+
+FIELD_TYPE_TO_GETTER_TYPE = {
+  'boolean': 'bool',
+  'integer': 'int',
+  'double': 'double',
+  'string': 'std::string',
+  'string_list': 'login::StringList'
+}
+
+DISPATCH_EVENT_TEMPLATE = \
+"""  if (event == "%(event_id)s") {
+    %(method_name)s();
+    return;
+  }"""
+
+def GetCommonSubistitutions(declaration):
+  subs = {}
+  subs['year'] = datetime.date.today().year
+  subs['class_name'] = declaration.view_model_class
+  subs['source'] = declaration.path
+  return subs
+
+def FieldNameToConstantName(field_name):
+  return 'kContextKey' + util.ToUpperCamelCase(field_name)
+
+def GenContextKeysDeclarations(fields):
+  return '\n'.join(
+      (CONTEXT_KEY_DECLARATION_TEMPLATE % \
+          FieldNameToConstantName(f.name) for f in fields))
+
+def GenChildrenForwardDeclarations(children):
+  lines = []
+  for declaration in set(children.itervalues()):
+    lines.append(CHILD_FORWARD_DECLARATION_TEMPLATE % {
+                     'child_type': declaration.view_model_class
+                 })
+  return '\n'.join(lines)
+
+def ChildIdToChildGetterName(id):
+  return 'Get%s' % util.ToUpperCamelCase(id)
+
+def GenChildrenGettersDeclarations(children):
+  lines = []
+  for id, declaration in children.iteritems():
+    lines.append(CHILD_GETTER_DECLARATION_TEMPLATE % {
+                     'child_type': declaration.view_model_class,
+                     'method_name': ChildIdToChildGetterName(id)
+                 })
+  return '\n'.join(lines)
+
+def FieldNameToGetterName(field_name):
+  return 'Get%s' % util.ToUpperCamelCase(field_name)
+
+def GenContextGettersDeclarations(context_fields):
+  lines = []
+  for field in context_fields:
+    lines.append(CONTEXT_VALUE_GETTER_DECLARATION_TEMPLATE % {
+                     'type': FIELD_TYPE_TO_GETTER_TYPE[field.type],
+                     'method_name': FieldNameToGetterName(field.name)
+                 })
+  return '\n'.join(lines)
+
+def EventIdToMethodName(event):
+  return 'On' + util.ToUpperCamelCase(event)
+
+def GenEventHandlersDeclarations(events):
+  lines = []
+  for event in events:
+    lines.append(EVENT_HANDLER_DECLARATION_TEMPLATE %
+                     EventIdToMethodName(event))
+  return '\n'.join(lines)
+
+def GenHFile(declaration):
+  subs = GetCommonSubistitutions(declaration)
+  subs['include_guard'] = \
+      util.PathToIncludeGuard(declaration.view_model_include_path)
+  subs['context_keys'] = GenContextKeysDeclarations(declaration.fields)
+  subs['children_forward_declarations'] = \
+      GenChildrenForwardDeclarations(declaration.children)
+  subs['children_getters'] = \
+      GenChildrenGettersDeclarations(declaration.children);
+  subs['context_getters'] = \
+      GenContextGettersDeclarations(declaration.fields);
+  subs['event_handlers'] = GenEventHandlersDeclarations(declaration.events)
+  subs['export_h_include_path'] = declaration.export_h_include_path
+  subs['export_macro'] = declaration.component_export_macro
+  return H_FILE_TEMPLATE % subs
+
+def GenContextKeysDefinitions(declaration):
+  lines = []
+  for field in declaration.fields:
+    definition = CONTEXT_KEY_DEFINITION_TEMPLATE % {
+      'class_name': declaration.view_model_class,
+      'name': FieldNameToConstantName(field.name),
+      'value': field.id
+    }
+    lines.append(definition)
+  return '\n'.join(lines)
+
+def GenChildrenIncludes(children):
+  lines = []
+  for declaration in set(children.itervalues()):
+    lines.append('#include "%s"' % declaration.view_model_include_path)
+  return '\n'.join(lines)
+
+def GenContextFieldInitialization(field):
+  lines = []
+  key_constant = FieldNameToConstantName(field.name)
+  setter_method = 'Set' + util.ToUpperCamelCase(field.type)
+  if field.type == 'string_list':
+    lines.append('  {')
+    lines.append('    std::vector<std::string> defaults;')
+    for s in field.default_value:
+      lines.append('    defaults.push_back("%s");' % s)
+    lines.append('    context().%s(%s, defaults);' %
+                     (setter_method, key_constant))
+    lines.append('  }')
+  else:
+    setter = '  context().%s(%s, ' % (setter_method, key_constant)
+    if field.type in ['integer', 'double']:
+      setter += str(field.default_value)
+    elif field.type == 'boolean':
+      setter += 'true' if field.default_value else 'false'
+    else:
+      assert field.type == 'string'
+      setter += '"%s"' % field.default_value
+    setter += ");"
+    lines.append(setter)
+  return '\n'.join(lines)
+
+def GenChildrenGettersDefenitions(declaration):
+  lines = []
+  for id, child in declaration.children.iteritems():
+    lines.append(CHILD_GETTER_DEFINITION_TEMPLATE % {
+                     'child_type': child.view_model_class,
+                     'class_name': declaration.view_model_class,
+                     'method_name': ChildIdToChildGetterName(id),
+                     'child_id': id
+                 });
+  return '\n'.join(lines)
+
+def GenContextGettersDefinitions(declaration):
+  lines = []
+  for field in declaration.fields:
+    lines.append(CONTEXT_VALUE_GETTER_DEFINITION_TEMPLATE % {
+                     'type': FIELD_TYPE_TO_GETTER_TYPE[field.type],
+                     'class_name': declaration.view_model_class,
+                     'method_name': FieldNameToGetterName(field.name),
+                     'context_getter': 'Get' + util.ToUpperCamelCase(
+                                                        field.type),
+                     'key_constant': FieldNameToConstantName(field.name)
+                 });
+  return '\n'.join(lines)
+
+def GenEventDispatcherBody(events):
+  lines = []
+  for event in events:
+    lines.append(DISPATCH_EVENT_TEMPLATE % {
+                     'event_id': util.ToLowerCamelCase(event),
+                     'method_name': EventIdToMethodName(event)
+                 });
+  return '\n'.join(lines)
+
+def GenCCFile(declaration):
+  subs = GetCommonSubistitutions(declaration)
+  subs['header_path'] = declaration.view_model_include_path
+  subs['context_keys'] = GenContextKeysDefinitions(declaration)
+  subs['children_includes'] = GenChildrenIncludes(declaration.children)
+  initializations = [GenContextFieldInitialization(field) \
+                         for field in declaration.fields]
+  initializations.append('  base::DictionaryValue diff;');
+  initializations.append('  context().GetChangesAndReset(&diff);');
+  subs['constructor_body'] = '\n'.join(initializations)
+  subs['children_getters'] = GenChildrenGettersDefenitions(declaration)
+  subs['context_getters'] = GenContextGettersDefinitions(declaration)
+  subs['event_dispatcher_body'] = GenEventDispatcherBody(declaration.events)
+  return CC_FILE_TEMPLATE % subs
+
+def ListOutputs(declaration, destination):
+  dirname = os.path.join(destination, os.path.dirname(declaration.path))
+  h_file_path = os.path.join(dirname, declaration.view_model_h_name)
+  cc_file_path = os.path.join(dirname, declaration.view_model_cc_name)
+  return [h_file_path, cc_file_path]
+
+def Gen(declaration, destination):
+  h_file_path, cc_file_path = ListOutputs(declaration, destination)
+  util.CreateDirIfNotExists(os.path.dirname(h_file_path))
+  open(h_file_path, 'w').write(GenHFile(declaration))
+  open(cc_file_path, 'w').write(GenCCFile(declaration))
+
diff --git a/components/webui_generator/generator/web_ui_view.py b/components/webui_generator/generator/web_ui_view.py
new file mode 100644
index 0000000..f534cae
--- /dev/null
+++ b/components/webui_generator/generator/web_ui_view.py
@@ -0,0 +1,205 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import datetime
+import json
+import os
+import os.path
+import util
+import html_view
+
+H_FILE_TEMPLATE = \
+"""// Copyright %(year)d The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// NOTE: this file is generated from "%(source)s". Do not modify directly.
+
+#ifndef %(include_guard)s
+#define %(include_guard)s
+
+#include "base/macros.h"
+#include "components/webui_generator/web_ui_view.h"
+#include "%(export_h_include_path)s"
+
+namespace gen {
+
+class %(export_macro)s %(class_name)s : public ::webui_generator::WebUIView {
+ public:
+  %(class_name)s(content::WebUI* web_ui);
+  %(class_name)s(content::WebUI* web_ui, const std::string& id);
+
+ protected:
+  void AddLocalizedValues(::login::LocalizedValuesBuilder* builder) override;
+  void AddResources(ResourcesMap* resources_map) override;
+  void CreateAndAddChildren() override;
+  ::webui_generator::ViewModel* CreateViewModel() override;
+  std::string GetType() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(%(class_name)s);
+};
+
+}  // namespace gen
+
+#endif  // %(include_guard)s
+"""
+
+CC_FILE_TEMPLATE = \
+"""// Copyright %(year)d The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// NOTE: this file is generated from "%(source)s". Do not modify directly.
+
+#include "%(header_path)s"
+
+#include "content/public/browser/web_ui_data_source.h"
+#include "content/public/browser/web_contents.h"
+#include "components/login/localized_values_builder.h"
+#include "grit/components_strings.h"
+%(includes)s
+
+namespace {
+
+const char kHTMLDoc[] = "%(html_doc)s";
+const char kJSDoc[] = "%(js_doc)s";
+
+}  // namespace
+
+namespace gen {
+
+%(class_name)s::%(class_name)s(content::WebUI* web_ui)
+    : webui_generator::WebUIView(web_ui, "WUG_ROOT") {
+}
+
+%(class_name)s::%(class_name)s(content::WebUI* web_ui, const std::string& id)
+    : webui_generator::WebUIView(web_ui, id) {
+}
+
+void %(class_name)s::AddLocalizedValues(
+    ::login::LocalizedValuesBuilder* builder) {
+%(add_localized_values_body)s
+}
+
+void %(class_name)s::AddResources(ResourcesMap* resources_map) {
+%(add_resources_body)s
+}
+
+void %(class_name)s::CreateAndAddChildren() {
+%(create_and_add_children_body)s
+}
+
+::webui_generator::ViewModel* %(class_name)s::CreateViewModel() {
+%(create_view_model_body)s
+}
+
+std::string %(class_name)s::GetType() {
+%(get_type_body)s
+}
+
+}  // namespace gen
+"""
+
+ADD_LOCALIZED_VALUE_TEMPLATE = \
+"""  builder->Add("%(string_name)s", %(resource_id)s);"""
+
+ADD_RESOURCE_TEMPLATE = \
+"""  (*resources_map)["%(path)s"] = scoped_refptr<base::RefCountedMemory>(
+    new base::RefCountedStaticMemory(%(const)s, arraysize(%(const)s) - 1));"""
+
+CREATE_AND_ADD_CHILD_TEMPLATE = \
+"""  AddChild(new gen::%(child_class)s(web_ui(), "%(child_id)s"));"""
+
+CREATE_VIEW_MODEL_BODY_TEMPLATE = \
+"""  return gen::%s::Create(web_ui()->GetWebContents()->GetBrowserContext());"""
+
+def GetCommonSubistitutions(declaration):
+  subs = {}
+  subs['year'] = datetime.date.today().year
+  subs['class_name'] = declaration.webui_view_class
+  subs['source'] = declaration.path
+  return subs
+
+
+def GenHFile(declaration):
+  subs = GetCommonSubistitutions(declaration)
+  subs['include_guard'] = util.PathToIncludeGuard(
+                              declaration.webui_view_include_path)
+  subs['export_h_include_path'] = declaration.export_h_include_path
+  subs['export_macro'] = declaration.component_export_macro
+  return H_FILE_TEMPLATE % subs
+
+def GenIncludes(declaration):
+  lines = []
+  lines.append('#include "%s"' % declaration.view_model_include_path)
+  children_declarations = set(declaration.children.itervalues())
+  for child in children_declarations:
+    lines.append('#include "%s"' % child.webui_view_include_path)
+  return '\n'.join(lines)
+
+def GenAddLocalizedValuesBody(declaration):
+  lines = []
+  resource_id_prefix = "IDS_WUG_" + declaration.type.upper() + "_"
+  for name in declaration.strings:
+    resource_id = resource_id_prefix + name.upper()
+    subs = {
+      'string_name': util.ToLowerCamelCase(name),
+      'resource_id': resource_id
+    }
+    lines.append(ADD_LOCALIZED_VALUE_TEMPLATE % subs)
+  return '\n'.join(lines)
+
+def GenAddResourcesBody(declaration):
+  lines = []
+  html_path = declaration.html_view_html_include_path
+  lines.append(ADD_RESOURCE_TEMPLATE % { 'path': html_path,
+                                         'const': 'kHTMLDoc' })
+  js_path = declaration.html_view_js_include_path
+  lines.append(ADD_RESOURCE_TEMPLATE % { 'path': js_path,
+                                         'const': 'kJSDoc' })
+  return '\n'.join(lines)
+
+def GenCreateAndAddChildrenBody(children):
+  lines = []
+  for id, declaration in children.iteritems():
+    subs = {
+      'child_class': declaration.webui_view_class,
+      'child_id': id
+    }
+    lines.append(CREATE_AND_ADD_CHILD_TEMPLATE % subs)
+  return '\n'.join(lines)
+
+def EscapeStringForCLiteral(string):
+  return json.dumps(string)[1:][:-1]
+
+def GenCCFile(declaration):
+  subs = GetCommonSubistitutions(declaration)
+  subs['header_path'] = declaration.webui_view_include_path
+  subs['includes'] = GenIncludes(declaration)
+  subs['add_localized_values_body'] = \
+    GenAddLocalizedValuesBody(declaration)
+  subs['add_resources_body'] = \
+    GenAddResourcesBody(declaration)
+  subs['create_and_add_children_body'] = \
+    GenCreateAndAddChildrenBody(declaration.children)
+  subs['create_view_model_body'] = \
+    CREATE_VIEW_MODEL_BODY_TEMPLATE % declaration.view_model_class
+  subs['get_type_body'] = '    return "%s";' % declaration.type
+  subs['html_doc'] = EscapeStringForCLiteral(html_view.GenHTMLFile(declaration))
+  subs['js_doc'] = EscapeStringForCLiteral(html_view.GenJSFile(declaration))
+  return CC_FILE_TEMPLATE % subs
+
+def ListOutputs(declaration, destination):
+  dirname = os.path.join(destination, os.path.dirname(declaration.path))
+  h_file_path = os.path.join(dirname, declaration.webui_view_h_name)
+  cc_file_path = os.path.join(dirname, declaration.webui_view_cc_name)
+  return [h_file_path, cc_file_path]
+
+def Gen(declaration, destination):
+  h_file_path, cc_file_path = ListOutputs(declaration, destination)
+  util.CreateDirIfNotExists(os.path.dirname(h_file_path))
+  open(h_file_path, 'w').write(GenHFile(declaration))
+  open(cc_file_path, 'w').write(GenCCFile(declaration))
+
diff --git a/components/webui_generator/generator/wug.gni b/components/webui_generator/generator/wug.gni
new file mode 100644
index 0000000..a4b4a2d
--- /dev/null
+++ b/components/webui_generator/generator/wug.gni
@@ -0,0 +1,112 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Generates native and HTML/JS supporting code for Web UI element from element's
+# declaration JSON file.
+#
+# Parameters:
+#
+#   source (required)
+#      declaration file.
+#
+# Example:
+# wug("some_type_wug_generated") {
+#   source = "some_type.json"
+# }
+#
+# Target's name should be deduced from declaration file name by removing
+# extension and adding '_wug_generated' prefix. This is needed to properly
+# handle dependencies between declaration files and their imports.
+#
+# For declaration file with a full path 'src/full/path/some_type.json' 5 files
+# will be generated and compiled:
+#   $root_gen_dir/wug/full/path/some_type_export.h
+#   $root_gen_dir/wug/full/path/some_type_view.h
+#   $root_gen_dir/wug/full/path/some_type_view_model.cc
+#   $root_gen_dir/wug/full/path/some_type_view_model.h
+#   $root_gen_dir/wug/full/path/some_type_webui_view.cc
+
+template("wug") {
+  declaration_path = invoker.source
+  generator_dir = "//components/webui_generator/generator"
+  generator_path = "$generator_dir/gen_sources.py"
+  src_root = rebase_path("//", root_build_dir)
+
+  helper_path = "$generator_dir/build_helper.py"
+  target_name = "${target_name}"
+  action_name = target_name + "_gen"
+  out_dir = "$root_gen_dir/wug"
+
+  helper_args = [
+    rebase_path(declaration_path, root_build_dir),
+    "--destination",
+    out_dir,
+    "--root",
+    src_root,
+    "--gn",
+    "--output",
+  ]
+
+  expected_target_name =
+      exec_script(helper_path, helper_args + [ "target_name" ], "trim string")
+  assert(target_name == expected_target_name,
+         "Wrong target name. " + "Expected '" + expected_target_name +
+             "', got '" + target_name + "'.")
+
+  action(action_name) {
+    script = generator_path
+    sources = [
+      "$generator_dir/declaration.py",
+      "$generator_dir/export_h.py",
+      "$generator_dir/html_view.py",
+      "$generator_dir/util.py",
+      "$generator_dir/view_model.py",
+      "$generator_dir/web_ui_view.py",
+    ]
+    inputs = [
+      declaration_path,
+    ]
+    inputs +=
+        exec_script(helper_path, helper_args + [ "imports" ], "list lines")
+    common_prefix = process_file_template(
+            [ declaration_path ],
+            "$out_dir/{{source_root_relative_dir}}/{{source_name_part}}_")
+    common_prefix = common_prefix[0]
+    outputs = [
+      common_prefix + "export.h",
+      common_prefix + "view_model.h",
+      common_prefix + "view_model.cc",
+      common_prefix + "web_ui_view.h",
+      common_prefix + "web_ui_view.cc",
+    ]
+    args = [
+      rebase_path(declaration_path, root_build_dir),
+      "--root",
+      src_root,
+      "--destination",
+      out_dir,
+    ]
+  }
+
+  component(target_name) {
+    sources = get_target_outputs(":$action_name")
+    defines = [ exec_script(helper_path,
+                            helper_args + [ "impl_macro" ],
+                            "trim string") ]
+    deps = [
+      "//base",
+      "//components/login",
+      "//components/strings",
+    ]
+    deps += exec_script(helper_path,
+                        helper_args + [ "import_dependencies" ],
+                        "list lines")
+    public_deps = [
+      "//components/webui_generator",
+    ]
+
+    all_dependent_configs =
+        [ "//components/webui_generator:wug_generated_config" ]
+  }
+}
diff --git a/components/webui_generator/generator/wug.gypi b/components/webui_generator/generator/wug.gypi
new file mode 100644
index 0000000..a40577c
--- /dev/null
+++ b/components/webui_generator/generator/wug.gypi
@@ -0,0 +1,118 @@
+# Copyright (c) 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This file included into a targets definition creates a target that generates
+# native and HTML/JS supporting code for Web UI element from element's
+# declaration JSON file.
+#
+# Example:
+# 'targets': [
+#   ...
+#   {
+#     'variables': {
+#       'declaration_file': 'path/to/file.json'
+#     }
+#     'includes': ['path/to/this/file.gypi']
+#   },
+#   ...
+# ]
+#
+# Such inclusion creates a target, which name is deduced from declaration file
+# name by removing extension and adding '_wug_generated' prefix, e.g. for
+# declaration file named 'some_type.json' will be created target named
+# 'some_type_wug_generated'. This is needed to properly handle dependencies
+# between declaration files and their imports.
+#
+# For declaration file with a full path 'src/full/path/some_type.json' 5 files
+# will be generated and compiled:
+#   <(SHARED_INTERMEDIATE_DIR)/wug/full/path/some_type_export.h
+#   <(SHARED_INTERMEDIATE_DIR)/wug/full/path/some_type_view.h
+#   <(SHARED_INTERMEDIATE_DIR)/wug/full/path/some_type_view_model.cc
+#   <(SHARED_INTERMEDIATE_DIR)/wug/full/path/some_type_view_model.h
+#   <(SHARED_INTERMEDIATE_DIR)/wug/full/path/some_type_webui_view.cc
+
+{
+  'variables': {
+    'generator_dir': '<(DEPTH)/components/webui_generator/generator',
+    'helper_path': '<(generator_dir)/build_helper.py',
+    'generator_path': '<(generator_dir)/gen_sources.py',
+    'out_dir': '<(SHARED_INTERMEDIATE_DIR)/wug',
+    'helper_cl': 'python <(helper_path) --root=<(DEPTH) <(declaration_file)',
+    'dirname': '<(out_dir)/<!(<(helper_cl) --output=dirname)',
+    'view_cc': '<(dirname)/<!(<(helper_cl) --output=view_cc)',
+    'view_h': '<(dirname)/<!(<(helper_cl) --output=view_h)',
+    'model_cc': '<(dirname)/<!(<(helper_cl) --output=model_cc)',
+    'model_h': '<(dirname)/<!(<(helper_cl) --output=model_h)',
+    'export_h': '<(dirname)/<!(<(helper_cl) --output=export_h)',
+    'export_h': '<(dirname)/<!(<(helper_cl) --output=export_h)',
+    'impl_macro': '<!(<(helper_cl) --output=impl_macro)',
+  },
+  'target_name': '<!(<(helper_cl) --output=target_name)',
+  'type': '<(component)',
+  'sources': [
+    '<(view_cc)',
+    '<(view_h)',
+    '<(model_cc)',
+    '<(model_h)',
+    '<(export_h)',
+  ],
+  'defines': [
+    '<(impl_macro)',
+  ],
+  'actions': [
+    {
+      'action_name': 'gen_files',
+      'inputs': [
+        '<(generator_path)',
+        '<(generator_dir)/declaration.py',
+        '<(generator_dir)/export_h.py',
+        '<(generator_dir)/html_view.py',
+        '<(generator_dir)/util.py',
+        '<(generator_dir)/view_model.py',
+        '<(generator_dir)/web_ui_view.py',
+        '<(declaration_file)',
+      ],
+      'outputs': [
+        '<(view_cc)',
+        '<(view_h)',
+        '<(model_cc)',
+        '<(model_h)',
+        '<(export_h)',
+      ],
+      'action': [
+        'python',
+        '<(generator_path)',
+        '--root=<(DEPTH)',
+        '--destination=<(out_dir)',
+        '<(declaration_file)'
+      ],
+      'message': 'Generating C++ code from <(declaration_file).',
+    },
+  ],
+  'dependencies': [
+    '<(DEPTH)/base/base.gyp:base',
+    '<(DEPTH)/components/components.gyp:login',
+    '<(DEPTH)/components/components.gyp:webui_generator',
+    '<(DEPTH)/components/components_strings.gyp:components_strings',
+    '<(DEPTH)/skia/skia.gyp:skia',
+    '<!@(<(helper_cl) --output=import_dependencies)',
+  ],
+  'include_dirs': [
+    '<(DEPTH)',
+    '<(out_dir)',
+  ],
+  'all_dependent_settings': {
+    'include_dirs': [
+      '<(DEPTH)',
+      '<(out_dir)',
+    ],
+  },
+  'export_dependent_settings': [
+    '<(DEPTH)/components/components.gyp:webui_generator',
+    '<(DEPTH)/components/components.gyp:login',
+  ],
+  # This target exports a hard dependency because it generates header
+  # files.
+  'hard_dependency': 1,
+}
diff --git a/components/webui_generator/resources/context.html b/components/webui_generator/resources/context.html
new file mode 100644
index 0000000..e1631b2
--- /dev/null
+++ b/components/webui_generator/resources/context.html
@@ -0,0 +1,5 @@
+<!-- Copyright 2015 The Chromium Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style license that can be
+     found in the LICENSE file. -->
+<script src="context.js"></script>
+
diff --git a/components/webui_generator/resources/context.js b/components/webui_generator/resources/context.js
new file mode 100644
index 0000000..0bd28f1
--- /dev/null
+++ b/components/webui_generator/resources/context.js
@@ -0,0 +1,21 @@
+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+(function(global) {
+  var has_cr = !!global.cr;
+  var cr_define_bckp = null;
+  if (has_cr && global.cr.define)
+    cr_define_bckp = global.cr.define;
+  if (!has_cr)
+     global.cr = {}
+  global.cr.define = function(_, define) {
+    global.wug = global.wug || {}
+    global.wug.Context = define().ScreenContext;
+  }
+<include src="../../../chrome/browser/resources/chromeos/login/screen_context.js">
+  if (!has_cr)
+    delete global.cr;
+  if (cr_define_bckp)
+    global.cr.define = cr_define_bckp;
+})(this);
diff --git a/components/webui_generator/resources/webui-view.html b/components/webui_generator/resources/webui-view.html
new file mode 100644
index 0000000..b07fa5c
--- /dev/null
+++ b/components/webui_generator/resources/webui-view.html
@@ -0,0 +1,10 @@
+<!-- Copyright 2015 The Chromium Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style license that can be
+     found in the LICENSE file. -->
+
+<link rel="import" href="chrome://resources/polymer/polymer/polymer.html">
+<link rel="import" href="context.html">
+
+<polymer-element name="webui-view"></polymer-element>
+<script src="webui-view.js"></script>
+
diff --git a/components/webui_generator/resources/webui-view.js b/components/webui_generator/resources/webui-view.js
new file mode 100644
index 0000000..99a033f
--- /dev/null
+++ b/components/webui_generator/resources/webui-view.js
@@ -0,0 +1,189 @@
+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+Polymer('webui-view', (function() {
+  /** @const */ var CALLBACK_CONTEXT_CHANGED = 'contextChanged';
+  /** @const */ var CALLBACK_READY = 'ready';
+
+  return {
+    /** @const */
+    CALLBACK_EVENT_FIRED: 'eventFired',
+
+    /**
+     * Dictionary of context observers that are methods of |this| bound to
+     * |this|.
+     */
+    contextObservers_: null,
+
+    /**
+     * Full path to the element in views hierarchy.
+     */
+    path_: null,
+
+    /**
+     * Whether DOM is ready.
+     */
+    domReady_: false,
+
+    /**
+     * Context used for sharing data with native backend.
+     */
+    context: null,
+
+    /**
+     * Internal storage of |this.context|.
+     * |C| bound to the native part of the context, that means that all the
+     * changes in the native part appear in |C| automatically. Reverse is not
+     * true, you should use:
+     *    this.context.set(...);
+     *    this.context.commitContextChanges();
+     * to send updates to the native part.
+     */
+    C: null,
+
+    ready: function() {
+      this.context = new wug.Context;
+      this.C = this.context.storage_;
+      this.contextObservers_ = {};
+    },
+
+    /**
+     * One of element's lifecycle methods.
+     */
+    domReady: function() {
+      var id = this.getAttribute('wugid');
+      if (!id) {
+        console.error('"wugid" attribute is missing.');
+        return;
+      }
+      if (id == 'WUG_ROOT')
+        this.setPath_('WUG_ROOT');
+      this.domReady_ = true;
+      if (this.path_)
+        this.init_();
+    },
+
+    setPath_: function(path) {
+      this.path_ = path;
+      if (this.domReady_)
+        this.init_();
+    },
+
+    init_: function() {
+      this.initContext_();
+      this.initChildren_();
+      window[this.path_ + '$contextChanged'] =
+          this.onContextChanged_.bind(this);
+      this.initialize();
+      this.send(CALLBACK_READY);
+    },
+
+    fireEvent: function(_, _, source) {
+      this.send(this.CALLBACK_EVENT_FIRED, source.getAttribute('event'));
+    },
+
+    i18n: function(args) {
+      if (!(args instanceof Array))
+        args = [args];
+      args[0] = this.getType() + '$' + args[0];
+      return loadTimeData.getStringF.apply(loadTimeData, args);
+    },
+
+    /**
+     * Sends message to Chrome, adding needed prefix to message name. All
+     * arguments after |messageName| are packed into message parameters list.
+     *
+     * @param {string} messageName Name of message without a prefix.
+     * @param {...*} varArgs parameters for message.
+     * @private
+     */
+    send: function(messageName, varArgs) {
+      if (arguments.length == 0)
+        throw Error('Message name is not provided.');
+      var fullMessageName = this.path_ + '$' + messageName;
+      var payload = Array.prototype.slice.call(arguments, 1);
+      chrome.send(fullMessageName, payload);
+    },
+
+    /**
+     * Starts observation of property with |key| of the context attached to
+     * current screen. In contrast with "wug.Context.addObserver" this method
+     * can automatically detect if observer is method of |this| and make
+     * all needed actions to make it work correctly. So there is no need in
+     * binding method to |this| before adding it. For example, if |this| has
+     * a method |onKeyChanged_|, you can do:
+     *
+     *   this.addContextObserver('key', this.onKeyChanged_);
+     *   ...
+     *   this.removeContextObserver('key', this.onKeyChanged_);
+     *
+     * instead of:
+     *
+     *   this.keyObserver_ = this.onKeyChanged_.bind(this);
+     *   this.addContextObserver('key', this.keyObserver_);
+     *   ...
+     *   this.removeContextObserver('key', this.keyObserver_);
+     *
+     * @private
+     */
+    addContextObserver: function(key, observer) {
+      var realObserver = observer;
+      var propertyName = this.getPropertyNameOf_(observer);
+      if (propertyName) {
+        if (!this.contextObservers_.hasOwnProperty(propertyName))
+          this.contextObservers_[propertyName] = observer.bind(this);
+        realObserver = this.contextObservers_[propertyName];
+      }
+      this.context.addObserver(key, realObserver);
+    },
+
+    /**
+     * Removes |observer| from the list of context observers. Observer could be
+     * a method of |this| (see comment to |addContextObserver|).
+     * @private
+     */
+    removeContextObserver: function(observer) {
+      var realObserver = observer;
+      var propertyName = this.getPropertyNameOf_(observer);
+      if (propertyName) {
+        if (!this.contextObservers_.hasOwnProperty(propertyName))
+          return;
+        realObserver = this.contextObservers_[propertyName];
+        delete this.contextObservers_[propertyName];
+      }
+      this.context.removeObserver(realObserver);
+    },
+
+    /**
+     * Sends recent context changes to C++ handler.
+     * @private
+     */
+    commitContextChanges: function() {
+      if (!this.context.hasChanges())
+        return;
+      this.send(CALLBACK_CONTEXT_CHANGED, this.context.getChangesAndReset());
+    },
+
+    /**
+     * Called when context changed on C++ side.
+     */
+    onContextChanged_: function(diff) {
+      var changedKeys = this.context.applyChanges(diff);
+      this.contextChanged(changedKeys);
+    },
+
+    /**
+     * If |value| is the value of some property of |this| returns property's
+     * name. Otherwise returns empty string.
+     * @private
+     */
+    getPropertyNameOf_: function(value) {
+      for (var key in this)
+        if (this[key] === value)
+          return key;
+      return '';
+    }
+  };
+})());
+
diff --git a/components/webui_generator/view.cc b/components/webui_generator/view.cc
new file mode 100644
index 0000000..a335ef5
--- /dev/null
+++ b/components/webui_generator/view.cc
@@ -0,0 +1,102 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/webui_generator/view.h"
+
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/webui_generator/view_model.h"
+
+namespace webui_generator {
+
+View::View(const std::string& id)
+    : parent_(NULL),
+      id_(id),
+      ready_children_(0),
+      view_model_ready_(false),
+      ready_(false),
+      weak_factory_(this) {
+}
+
+View::~View() {
+}
+
+void View::Init() {
+  CreateAndAddChildren();
+
+  if (!IsRootView())
+    path_ = parent_->path() + "$";
+
+  path_ += id_;
+  view_model_.reset(CreateViewModel());
+  view_model_->SetView(this);
+
+  for (auto& id_child : children_)
+    id_child.second->Init();
+
+  if (children_.empty())
+    OnChildrenReady();
+}
+
+bool View::IsRootView() const {
+  return !parent_;
+}
+
+ViewModel* View::GetViewModel() const {
+  return view_model_.get();
+}
+
+void View::OnViewModelReady() {
+  view_model_ready_ = true;
+  if (ready_children_ == static_cast<int>(children_.size()))
+    OnReady();
+}
+
+View* View::GetChild(const std::string& id) const {
+  auto it = children_.find(id);
+  if (it == children_.end())
+    return nullptr;
+
+  return it->second;
+}
+
+void View::OnReady() {
+  if (ready_)
+    return;
+
+  ready_ = true;
+  if (!IsRootView())
+    parent_->OnChildReady(this);
+}
+
+void View::UpdateContext(const base::DictionaryValue& diff) {
+  DCHECK(ready_);
+  view_model_->UpdateContext(diff);
+}
+
+void View::HandleEvent(const std::string& event) {
+  DCHECK(ready_);
+  view_model_->OnEvent(event);
+}
+
+void View::AddChild(View* child) {
+  DCHECK(children_.find(child->id()) == children_.end());
+  DCHECK(!child->id().empty());
+  children_.set(child->id(), make_scoped_ptr(child));
+  child->set_parent(this);
+}
+
+void View::OnChildReady(View* child) {
+  ++ready_children_;
+  if (ready_children_ == static_cast<int>(children_.size()))
+    OnChildrenReady();
+}
+
+void View::OnChildrenReady() {
+  view_model_->OnChildrenReady();
+  if (view_model_ready_)
+    OnReady();
+}
+
+}  // namespace webui_generator
diff --git a/components/webui_generator/view.h b/components/webui_generator/view.h
new file mode 100644
index 0000000..b43ad74
--- /dev/null
+++ b/components/webui_generator/view.h
@@ -0,0 +1,116 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_WUG_VIEW_H_
+#define CHROME_BROWSER_UI_WEBUI_WUG_VIEW_H_
+
+#include "base/containers/scoped_ptr_hash_map.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "components/webui_generator/export.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+namespace webui_generator {
+
+class ViewModel;
+
+/**
+ * Base block of Web UI (in terms of Web UI Generator). Every View instance is
+ * associated with single ViewModel instance which provides a context for the
+ * view. Views are hierarchical. Every child of view has an unique id.
+ */
+class WUG_EXPORT View {
+ public:
+  explicit View(const std::string& id);
+  virtual ~View();
+
+  // Should be called before using the view. This method creates children (using
+  // CreateAndAddChildren() method) and a view-model (using CreateViewModel()
+  // method). Then it recursively calls Init() for the children. When
+  // all the children and the view-model are ready, OnReady() method is called.
+  // Overridden methods should call the base implementation.
+  virtual void Init();
+
+  // Root view is a view without parent.
+  // Root view should have id equal to "WUG_ROOT".
+  bool IsRootView() const;
+
+  ViewModel* GetViewModel() const;
+
+  // Called by view-model when it is ready.
+  void OnViewModelReady();
+
+  const std::string& id() const { return id_; }
+
+  // Every view has an unique path in a view hierarchy which is:
+  //  a) |id| for the root view;
+  //  b) concatenation of parent's path, $-sign and |id| for not-root views.
+  const std::string& path() const { return path_; }
+
+  // Returns a child with a given |id|. Returns |nullptr| if such child doesn't
+  // exist.
+  View* GetChild(const std::string& id) const;
+
+  // Called by view-model when it changes the context.
+  virtual void OnContextChanged(const base::DictionaryValue& diff) = 0;
+
+ protected:
+  // Called when view is ready, which means view-model and all children are
+  // ready. Overridden methods should call the base implementation.
+  virtual void OnReady();
+
+  // Forwards context changes stored in |diff| to view-model.
+  void UpdateContext(const base::DictionaryValue& diff);
+
+  // Forwards |event| to view-model.
+  void HandleEvent(const std::string& event);
+
+  bool ready() const { return ready_; }
+
+  base::ScopedPtrHashMap<std::string, View>& children() { return children_; }
+
+  // Adds |child| to the list of children of |this|. Can be called only from
+  // CreateAndAddChildren() override.
+  void AddChild(View* child);
+
+  virtual std::string GetType() = 0;
+
+  // Implementation should create an instance of view-model for this view.
+  virtual ViewModel* CreateViewModel() = 0;
+
+  // Implementation should create and add children to |this| view. This method
+  // is an only place where it is allowed to add children.
+  virtual void CreateAndAddChildren() = 0;
+
+ private:
+  // Called by |child| view, when it is ready.
+  void OnChildReady(View* child);
+
+  // Called when all the children created by CreatedAndAddChildren() are ready.
+  void OnChildrenReady();
+
+  void set_parent(View* parent) { parent_ = parent; }
+
+  View* parent_;
+  std::string id_;
+  std::string path_;
+
+  // Number of child views that are ready.
+  int ready_children_;
+
+  bool view_model_ready_;
+  bool ready_;
+  base::ScopedPtrHashMap<std::string, View> children_;
+  scoped_ptr<ViewModel> view_model_;
+  base::WeakPtrFactory<View> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(View);
+};
+
+}  // namespace webui_generator
+
+#endif  // CHROME_BROWSER_UI_WEBUI_WUG_VIEW_H_
diff --git a/components/webui_generator/view_model.cc b/components/webui_generator/view_model.cc
new file mode 100644
index 0000000..d81ce98
--- /dev/null
+++ b/components/webui_generator/view_model.cc
@@ -0,0 +1,106 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/webui_generator/view_model.h"
+
+#include "components/webui_generator/view.h"
+
+namespace webui_generator {
+
+ViewModel::ContextEditor::ContextEditor(ViewModel& view_model)
+    : view_model_(view_model), context_(view_model_.context()) {
+}
+
+ViewModel::ContextEditor::~ContextEditor() {
+  view_model_.CommitContextChanges();
+}
+
+const ViewModel::ContextEditor& ViewModel::ContextEditor::SetBoolean(
+    const KeyType& key,
+    bool value) const {
+  context_.SetBoolean(key, value);
+  return *this;
+}
+
+const ViewModel::ContextEditor& ViewModel::ContextEditor::SetInteger(
+    const KeyType& key,
+    int value) const {
+  context_.SetInteger(key, value);
+  return *this;
+}
+
+const ViewModel::ContextEditor& ViewModel::ContextEditor::SetDouble(
+    const KeyType& key,
+    double value) const {
+  context_.SetDouble(key, value);
+  return *this;
+}
+
+const ViewModel::ContextEditor& ViewModel::ContextEditor::SetString(
+    const KeyType& key,
+    const std::string& value) const {
+  context_.SetString(key, value);
+  return *this;
+}
+
+const ViewModel::ContextEditor& ViewModel::ContextEditor::SetString(
+    const KeyType& key,
+    const base::string16& value) const {
+  context_.SetString(key, value);
+  return *this;
+}
+
+const ViewModel::ContextEditor& ViewModel::ContextEditor::SetStringList(
+    const KeyType& key,
+    const StringList& value) const {
+  context_.SetStringList(key, value);
+  return *this;
+}
+
+const ViewModel::ContextEditor& ViewModel::ContextEditor::SetString16List(
+    const KeyType& key,
+    const String16List& value) const {
+  context_.SetString16List(key, value);
+  return *this;
+}
+
+ViewModel::ViewModel() : view_(nullptr) {
+}
+
+ViewModel::~ViewModel() {
+}
+
+void ViewModel::SetView(View* view) {
+  view_ = view;
+  Initialize();
+}
+
+void ViewModel::OnChildrenReady() {
+  OnAfterChildrenReady();
+  view_->OnViewModelReady();
+}
+
+void ViewModel::UpdateContext(const base::DictionaryValue& diff) {
+  std::vector<std::string> changed_keys;
+  context_.ApplyChanges(diff, &changed_keys);
+  OnContextChanged(changed_keys);
+}
+
+void ViewModel::OnEvent(const std::string& event) {
+}
+
+ViewModel::ContextEditor ViewModel::GetContextEditor() {
+  return ContextEditor(*this);
+}
+
+void ViewModel::CommitContextChanges() {
+  if (!context().HasChanges())
+    return;
+
+  base::DictionaryValue diff;
+  context().GetChangesAndReset(&diff);
+  view_->OnContextChanged(diff);
+}
+
+}  // namespace webui_generator
diff --git a/components/webui_generator/view_model.h b/components/webui_generator/view_model.h
new file mode 100644
index 0000000..a7021e0
--- /dev/null
+++ b/components/webui_generator/view_model.h
@@ -0,0 +1,108 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_WUG_VIEW_MODEL_H_
+#define CHROME_BROWSER_UI_WEBUI_WUG_VIEW_MODEL_H_
+
+#include <vector>
+
+#include "base/macros.h"
+#include "components/login/screens/screen_context.h"
+#include "components/webui_generator/export.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+namespace webui_generator {
+
+using Context = login::ScreenContext;
+class View;
+
+// Base class for view-model. Usually View is responsible for creating and
+// initializing instances of this class.
+class WUG_EXPORT ViewModel {
+ public:
+  ViewModel();
+  virtual ~ViewModel();
+
+  void SetView(View* view);
+
+  // Called by view to notify that children are ready.
+  void OnChildrenReady();
+
+  // Called by view when it became bound (meaning that all changes in context
+  // will be reflected in view right after they are made).
+  virtual void OnViewBound() = 0;
+
+  // Notifies view-model about context changes happended on view side.
+  // View-model corrects its copy of context according to changes in |diff|.
+  void UpdateContext(const base::DictionaryValue& diff);
+
+  // Notifies view-model about |event| sent from view.
+  virtual void OnEvent(const std::string& event);
+
+ protected:
+  // Scoped context editor, which automatically commits all pending
+  // context changes on destruction.
+  class ContextEditor {
+   public:
+    using KeyType = ::login::ScreenContext::KeyType;
+    using String16List = ::login::String16List;
+    using StringList = ::login::StringList;
+
+    explicit ContextEditor(ViewModel& screen);
+    ~ContextEditor();
+
+    const ContextEditor& SetBoolean(const KeyType& key, bool value) const;
+    const ContextEditor& SetInteger(const KeyType& key, int value) const;
+    const ContextEditor& SetDouble(const KeyType& key, double value) const;
+    const ContextEditor& SetString(const KeyType& key,
+                                   const std::string& value) const;
+    const ContextEditor& SetString(const KeyType& key,
+                                   const base::string16& value) const;
+    const ContextEditor& SetStringList(const KeyType& key,
+                                       const StringList& value) const;
+    const ContextEditor& SetString16List(const KeyType& key,
+                                         const String16List& value) const;
+
+   private:
+    ViewModel& view_model_;
+    Context& context_;
+  };
+
+  // This method is called in a time appropriate for initialization. At this
+  // point it is allowed to make changes in the context, but it is not allowed
+  // to access child view-models.
+  virtual void Initialize() = 0;
+
+  // This method is called when all children are ready.
+  virtual void OnAfterChildrenReady() = 0;
+
+  // This method is called after context was changed on view side.
+  // |chanaged_keys| contains a list of keys of changed fields.
+  virtual void OnContextChanged(const std::vector<std::string>& changed_keys) {}
+
+  Context& context() { return context_; }
+  const Context& context() const { return context_; }
+
+  View* view() const { return view_; }
+
+  // Returns scoped context editor. The editor or it's copies should not outlive
+  // current BaseScreen instance.
+  ContextEditor GetContextEditor();
+
+  // Notifies view about changes made in context.
+  void CommitContextChanges();
+
+ private:
+  Context context_;
+  View* view_;
+
+  DISALLOW_COPY_AND_ASSIGN(ViewModel);
+};
+
+}  // namespace webui_generator
+
+#endif  // CHROME_BROWSER_UI_WEBUI_WUG_VIEW_MODEL_H_
diff --git a/components/webui_generator/web_ui_view.cc b/components/webui_generator/web_ui_view.cc
new file mode 100644
index 0000000..54b8668
--- /dev/null
+++ b/components/webui_generator/web_ui_view.cc
@@ -0,0 +1,111 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/webui_generator/web_ui_view.h"
+
+#include "base/bind_helpers.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/login/localized_values_builder.h"
+#include "components/webui_generator/data_source_util.h"
+#include "components/webui_generator/view_model.h"
+
+namespace {
+
+const char kEventCallback[] = "eventFired";
+const char kContextChangedCallback[] = "contextChanged";
+const char kReadyCallback[] = "ready";
+
+const char kMethodContextChanged[] = "contextChanged";
+
+}  // namespace
+
+namespace webui_generator {
+
+WebUIView::WebUIView(content::WebUI* web_ui, const std::string& id)
+    : View(id), web_ui_(web_ui), html_ready_(false), view_bound_(false) {
+}
+
+WebUIView::~WebUIView() {
+}
+
+void WebUIView::Init() {
+  View::Init();
+  AddCallback(path() + "$" + kEventCallback, &WebUIView::HandleEvent);
+  AddCallback(path() + "$" + kContextChangedCallback,
+              &WebUIView::HandleContextChanged);
+  AddCallback(path() + "$" + kReadyCallback, &WebUIView::HandleHTMLReady);
+}
+
+void WebUIView::SetUpDataSource(content::WebUIDataSource* data_source) {
+  DCHECK(IsRootView());
+  webui_generator::SetUpDataSource(data_source);
+  ResourcesMap* resources_map = new ResourcesMap();
+  SetUpDataSourceInternal(data_source, resources_map);
+  data_source->SetRequestFilter(base::Bind(&WebUIView::HandleDataRequest,
+                                           base::Unretained(this),
+                                           base::Owned(resources_map)));
+}
+
+void WebUIView::OnReady() {
+  View::OnReady();
+  if (html_ready_)
+    Bind();
+}
+
+void WebUIView::OnContextChanged(const base::DictionaryValue& diff) {
+  if (view_bound_)
+    web_ui_->CallJavascriptFunction(path() + "$" + kMethodContextChanged, diff);
+
+  if (!pending_context_changes_)
+    pending_context_changes_.reset(new Context());
+
+  pending_context_changes_->ApplyChanges(diff, nullptr);
+}
+
+void WebUIView::SetUpDataSourceInternal(content::WebUIDataSource* data_source,
+                                        ResourcesMap* resources_map) {
+  base::DictionaryValue strings;
+  auto builder = make_scoped_ptr(
+      new ::login::LocalizedValuesBuilder(GetType() + "$", &strings));
+  AddLocalizedValues(builder.get());
+  data_source->AddLocalizedStrings(strings);
+  AddResources(resources_map);
+  for (auto& id_child : children()) {
+    static_cast<WebUIView*>(id_child.second)
+        ->SetUpDataSourceInternal(data_source, resources_map);
+  }
+}
+
+bool WebUIView::HandleDataRequest(
+    const ResourcesMap* resources,
+    const std::string& path,
+    const content::WebUIDataSource::GotDataCallback& got_data_callback) {
+  auto it = resources->find(path);
+
+  if (it == resources->end())
+    return false;
+
+  got_data_callback.Run(it->second.get());
+  return true;
+}
+
+void WebUIView::HandleHTMLReady() {
+  html_ready_ = true;
+  if (ready())
+    Bind();
+}
+
+void WebUIView::HandleContextChanged(const base::DictionaryValue* diff) {
+  UpdateContext(*diff);
+}
+
+void WebUIView::Bind() {
+  view_bound_ = true;
+  if (pending_context_changes_)
+    OnContextChanged(pending_context_changes_->storage());
+
+  GetViewModel()->OnViewBound();
+}
+
+}  // namespace webui_generator
diff --git a/components/webui_generator/web_ui_view.h b/components/webui_generator/web_ui_view.h
new file mode 100644
index 0000000..9fd26cf
--- /dev/null
+++ b/components/webui_generator/web_ui_view.h
@@ -0,0 +1,116 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_WUG_WEB_UI_VIEW_H_
+#define CHROME_BROWSER_UI_WEBUI_WUG_WEB_UI_VIEW_H_
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/containers/hash_tables.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted_memory.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/login/base_screen_handler_utils.h"
+#include "components/login/screens/screen_context.h"
+#include "components/webui_generator/export.h"
+#include "components/webui_generator/view.h"
+#include "content/public/browser/web_ui.h"
+#include "content/public/browser/web_ui_data_source.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+namespace content {
+class WebUI;
+}
+
+namespace login {
+class LocalizedValuesBuilder;
+}
+
+namespace webui_generator {
+
+using Context = login::ScreenContext;
+
+/**
+ * View implementation for the WebUI. Represents a single HTML element derieved
+ * from <web-ui-view>.
+ */
+class WUG_EXPORT WebUIView : public View {
+ public:
+  WebUIView(content::WebUI* web_ui, const std::string& id);
+  ~WebUIView() override;
+
+  // Should be called for |data_source|, where this views will be used.
+  // Sets up |data_source| for children of |this| as well, that is why this
+  // method only shouldn't be called for non-root views.
+  void SetUpDataSource(content::WebUIDataSource* data_source);
+
+  // Overridden from View:
+  void Init() override;
+
+ protected:
+  using ResourcesMap =
+      base::hash_map<std::string, scoped_refptr<base::RefCountedMemory>>;
+
+  content::WebUI* web_ui() { return web_ui_; }
+
+  template <typename T>
+  void AddCallback(const std::string& name, void (T::*method)()) {
+    base::Callback<void()> callback =
+        base::Bind(method, base::Unretained(static_cast<T*>(this)));
+    web_ui_->RegisterMessageCallback(
+        name, base::Bind(&::login::CallbackWrapper0, callback));
+  }
+
+  template <typename T, typename A1>
+  void AddCallback(const std::string& name, void (T::*method)(A1 arg1)) {
+    base::Callback<void(A1)> callback =
+        base::Bind(method, base::Unretained(static_cast<T*>(this)));
+    web_ui_->RegisterMessageCallback(
+        name, base::Bind(&::login::CallbackWrapper1<A1>, callback));
+  }
+
+  // Overridden from View:
+  void OnReady() override;
+  void OnContextChanged(const base::DictionaryValue& diff) override;
+
+  virtual void AddLocalizedValues(::login::LocalizedValuesBuilder* builder) = 0;
+  virtual void AddResources(ResourcesMap* resources_map) = 0;
+
+ private:
+  // Internal implementation of SetUpDataSource.
+  void SetUpDataSourceInternal(content::WebUIDataSource* data_source,
+                               ResourcesMap* resources_map);
+
+  // Called when corresponding <web-ui-view> is ready.
+  void HandleHTMLReady();
+
+  // Called when context is changed on JS side.
+  void HandleContextChanged(const base::DictionaryValue* diff);
+
+  // Called when both |this| and corresponding <web-ui-view> are ready.
+  void Bind();
+
+  // Request filter for data source. Filter is needed to answer with a generated
+  // HTML and JS code which is not kept in resources.
+  bool HandleDataRequest(
+      const ResourcesMap* resources,
+      const std::string& path,
+      const content::WebUIDataSource::GotDataCallback& got_data_callback);
+
+ private:
+  content::WebUI* web_ui_;
+  bool html_ready_;
+  bool view_bound_;
+  scoped_ptr<Context> pending_context_changes_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebUIView);
+};
+
+}  // namespace webui_generator
+
+#endif  // CHROME_BROWSER_UI_WEBUI_WUG_WEB_UI_VIEW_H_