Turn viewer and viewport service into core services.

Credit goes to @aaron on whose PR this is based. I realized, though, that viewer and viewport would be pretty hard and frustrating, so I chose to finish it myself.

Part of #1055

build-system/tasks/presubmit-checks.js

@@ -59,6 +59,25 @@ var forbiddenTerms = {
       'test/functional/test-url-replacements.js'
     ],
   },
+  'installViewerService': {
+    message: privateServiceFactory,
+    whitelist: [
+      'src/amp-core-service.js',
+      'src/service/history-impl.js',
+      'src/service/viewer-impl.js',
+      'src/service/viewport-impl.js',
+      'test/functional/test-cid.js',
+      'test/functional/test-viewport.js',
+      'extensions/amp-analytics/0.1/test/test-amp-analytics.js',
+    ],
+  },
+  'installViewportService': {
+    message: privateServiceFactory,
+    whitelist: [
+      'src/amp-core-service.js',
+      'src/service/viewport-impl.js',
+    ],
+  },
   // Privacy sensitive
   'cidFor': {
     message: requiresReviewPrivacy,
@@ -73,7 +92,7 @@ var forbiddenTerms = {
     message: requiresReviewPrivacy,
     whitelist: [
       'src/service/cid-impl.js',
-      'src/viewer.js',
+      'src/service/viewer-impl.js',
       'test/functional/test-cid.js',
     ],
   },

extensions/amp-analytics/0.1/test/test-amp-analytics.js

@@ -19,6 +19,7 @@ import {adopt} from '../../../../src/runtime';
 import {getService} from '../../../../src/service';
 import {markElementScheduledForTesting} from '../../../../src/service';
 import {installCidService} from '../../../../src/service/cid-impl';
+import {installViewerService} from '../../../../src/service/viewer-impl';
 import * as sinon from 'sinon';
 
 adopt(window);
@@ -47,6 +48,7 @@ describe('amp-analytics', function() {
     };
     windowApi.Object = window.Object;
     markElementScheduledForTesting(windowApi, 'amp-analytics');
+    installViewerService(windowApi);
     installCidService(windowApi);
     getService(windowApi, 'xhr', () => {return {
       fetchJson: url => Promise.resolve(JSON.parse(jsonMockResponses[url]))

src/amp-core-service.js

@@ -0,0 +1,31 @@
+/**
+ * Copyright 2015 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {installHistoryService} from './service/history-impl';
+import {installViewerService} from './service/viewer-impl';
+import {installViewportService} from './service/viewport-impl';
+
+
+/**
+ * Services that can be assumed are always available in AMP.
+ * They are installed in amp.js very early in the application lifecyle.
+ * @param {!Window} window
+ */
+export function installCoreServices(window) {
+  installViewerService(window);
+  installViewportService(window);
+  installHistoryService(window);
+}

src/amp.js

@@ -15,14 +15,11 @@
  */
 
 import './polyfills';
-
-import {installHistoryService} from './service/history-impl';
 import {installPullToRefreshBlocker} from './pull-to-refresh';
 import {performanceFor} from './performance';
-import {viewerFor} from './viewer';
 import {vsyncFor} from './vsync';
 import {templatesFor} from './template';
-
+import {installCoreServices} from './amp-core-service';
 import {installAd} from '../builtins/amp-ad';
 import {installGlobalClickListener} from './document-click';
 import {installImg} from '../builtins/amp-img';
@@ -47,8 +44,7 @@ try {
   perf.tick('is');
   installStyles(document, cssText, () => {
     try {
-      installHistoryService(window);
-      viewerFor(window);
+      installCoreServices(window);
       vsyncFor(window);
       templatesFor(window);
 

src/runtime.js

@@ -19,6 +19,7 @@ import {BaseTemplate, registerExtendedTemplate} from './template';
 import {assert} from './asserts';
 import {getMode} from './mode';
 import {installStyles} from './styles';
+import {installCoreServices} from './amp-core-service';
 import {isExperimentOn, toggleExperiment} from './experiments';
 import {performanceFor} from './performance';
 import {registerElement} from './custom-element';
@@ -93,6 +94,7 @@ export function adopt(global) {
   /** @const */
   global.AMP.assert = assert;
 
+  installCoreServices(global);
   const viewer = viewerFor(global);
 
   /** @const */

src/service/history-impl.js

@@ -19,7 +19,7 @@ import {assert} from '../asserts';
 import {getService} from '../service';
 import {log} from '../log';
 import {timer} from '../timer';
-import {viewerFor} from '../viewer';
+import {installViewerService} from './viewer-impl';
 
 
 /** @private @const */
@@ -638,7 +638,7 @@ export class HistoryBindingVirtual_ {
  * @private
  */
 function createHistory_(window) {
-  const viewer = viewerFor(window);
+  const viewer = installViewerService(window);
   let binding;
   if (viewer.isOvertakeHistory()) {
     binding = new HistoryBindingVirtual_(viewer);