Diagnostics: Add stubs for mojo interface provider

Bug: 1125150
Test: browser_tests --gtest_filter=DiagnosticsApp*
Change-Id: If4c41f6ececc2b635da5b9f63c698cad558cb501
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2411654
Commit-Queue: Zentaro Kavanagh <zentaro@chromium.org>
Reviewed-by: Bailey Berro <baileyberro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808161}

chrome/test/data/webui/chromeos/diagnostics/diagnostics_test.js

@@ -6,6 +6,9 @@
 import 'chrome://resources/mojo/mojo/public/js/mojo_bindings_lite.js';
 import 'chrome://diagnostics/diagnostics_app.js';
 
+import {SystemDataProviderInterface} from 'chrome://diagnostics/diagnostics_types.js';
+import {getSystemDataProvider, setSystemDataProviderForTesting} from 'chrome://diagnostics/mojo_interface_provider.js';
+
 suite('DiagnosticsAppTest', () => {
   /** @type {?DiagnosticsApp} */
   let page = null;
@@ -26,4 +29,14 @@ suite('DiagnosticsAppTest', () => {
     // capabilities to test.
     assertEquals('Diagnostics', page.$$('#header').textContent);
   });
-});
\ No newline at end of file
+});
+
+suite('FakeMojoProviderTest', () => {
+  test('SettingGettingTestProvider', () => {
+    // TODO(zentaro): Replace with fake when built.
+    let fake_provider =
+        /** @type {SystemDataProviderInterface} */ (new Object());
+    setSystemDataProviderForTesting(fake_provider);
+    assertEquals(fake_provider, getSystemDataProvider());
+  });
+});

chromeos/components/diagnostics_ui/resources/BUILD.gn

@@ -12,6 +12,8 @@ js_type_check("closure_compile_module") {
   deps = [
     ":diagnostics_app",
     ":diagnostics_card",
+    ":diagnostics_types",
+    ":mojo_interface_provider",
   ]
 }
 
@@ -28,6 +30,13 @@ js_library("diagnostics_card") {
   ]
 }
 
+js_library("diagnostics_types") {
+}
+
+js_library("mojo_interface_provider") {
+  deps = [ "//ui/webui/resources/js:cr.m" ]
+}
+
 html_to_js("web_components") {
   js_files = [
     "diagnostics_app.js",

chromeos/components/diagnostics_ui/resources/diagnostics_app_resources.grd

@@ -16,7 +16,9 @@
       <include name="IDR_DIAGNOSTICS_APP_ICON" file="app_icon_192.png" type="BINDATA" />
       <include name="IDR_DIAGNOSTICS_APP_INDEX_HTML" file="index.html" type="BINDATA" />
       <include name="IDR_DIAGNOSTICS_APP_JS" file="${root_gen_dir}/chromeos/components/diagnostics_ui/resources/diagnostics_app.js" use_base_dir="false" type="BINDATA"/>
+      <include name="IDR_DIAGNOSTICS_MOJO_INTERFACE_PROVIDER_JS" file="mojo_interface_provider.js" type="BINDATA"/>
       <include name="IDR_DIAGNOSTICS_SHARED_CSS_JS" file="${root_gen_dir}/chromeos/components/diagnostics_ui/resources/diagnostics_shared_css.js" use_base_dir="false" type="BINDDATA"/>
+      <include name="IDR_DIAGNOSTICS_TYPES_JS" file="diagnostics_types.js" type="BINDATA"/>
     </includes>
   </release>
 </grit>

chromeos/components/diagnostics_ui/resources/diagnostics_types.js

+// Copyright 2020 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.
+
+/**
+ * @fileoverview
+ * Type aliases for the mojo API.
+ *
+ * TODO(zentaro): When the fake API is replaced by mojo these can be
+ * re-aliased to the corresponding mojo types, or replaced by them.
+ */
+
+/**
+ * Type alias for the SystemDataProviderInterface.
+ * TODO(zentaro): Replace with a real mojo type when implemented.
+ * @typedef {!Object}
+ */
+export let SystemDataProviderInterface;

chromeos/components/diagnostics_ui/resources/mojo_interface_provider.js

+// Copyright 2020 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 {assert} from 'chrome://resources/js/assert.m.js';
+import {SystemDataProviderInterface} from './diagnostics_types.js'
+
+/**
+ * @fileoverview
+ * Provides singleton access to mojo interfaces with the ability
+ * to override them with test/fake implementations.
+ */
+
+/**
+ * @type {?SystemDataProviderInterface}
+ */
+let systemDataProvider = null;
+
+/**
+ * @param {!SystemDataProviderInterface} testProvider
+ */
+export function setSystemDataProviderForTesting(testProvider) {
+  systemDataProvider = testProvider;
+}
+
+/**
+ * @return {!SystemDataProviderInterface}
+ */
+export function getSystemDataProvider() {
+  // TODO(zentaro): Instantiate a real mojo interface here.
+  assert(!!systemDataProvider);
+
+  return systemDataProvider;
+}