[Contextual Search] Add Mojo-enabled API component.

components/contextual_search.gypi

+# 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.
+
+{
+  'targets': [
+    {
+      # GN: //components/contextual_search:browser
+      'target_name': 'contextual_search_browser',
+      'type': 'static_library',
+      'include_dirs': [
+        '..',
+      ],
+      'dependencies': [
+        'contextual_search_mojo_bindings',
+        '../base/base.gyp:base',
+      ],
+      'sources': [
+        'contextual_search/browser/contextual_search_js_api_service_impl.cc',
+        'contextual_search/browser/contextual_search_js_api_service_impl.h',
+      ],
+    },
+    {
+      # GN: //components/contextual_search:renderer
+      'target_name': 'contextual_search_renderer',
+      'type': 'static_library',
+      'include_dirs': [
+        '..',
+        '../third_party/WebKit',
+      ],
+      'dependencies': [
+        'contextual_search_mojo_bindings',
+        '../base/base.gyp:base',
+      ],
+      'sources': [
+        'contextual_search/renderer/contextual_search_wrapper.cc',
+        'contextual_search/renderer/contextual_search_wrapper.h',
+        'contextual_search/renderer/overlay_js_render_frame_observer.cc',
+        'contextual_search/renderer/overlay_js_render_frame_observer.h',
+        'contextual_search/renderer/overlay_page_notifier_service_impl.cc',
+        'contextual_search/renderer/overlay_page_notifier_service_impl.h',
+      ],
+    },
+    {
+      # GN version: //components/contextual_search:mojo_bindings
+      'target_name': 'contextual_search_mojo_bindings',
+      'type': 'static_library',
+      'sources': [
+        'contextual_search/common/contextual_search_js_api_service.mojom',
+        'contextual_search/common/overlay_page_notifier_service.mojom',
+      ],
+      'includes': [
+        '../third_party/mojo/mojom_bindings_generator.gypi',
+      ],
+    },
+  ],
+}