Introduce experiment flag for new window.context implementation

3p/integration.js

@@ -23,7 +23,9 @@
  */
 
 import './polyfills';
+import {AmpContext} from './ampcontext';
 import {installEmbedStateListener, manageWin} from './environment';
+import {isExperimentOn} from '../src/experiments';
 import {nonSensitiveDataPostMessage, listenParent} from './messaging';
 import {
   computeInMasterFrame,
@@ -151,6 +153,11 @@ import {zedo} from '../ads/zedo';
 import {zergnet} from '../ads/zergnet';
 import {zucks} from '../ads/zucks';
 
+
+/** @const {string} */
+const AMP_CONTEXT_EXPERIMENT = '3p-use-ampcontext';
+
+
 /**
  * Whether the embed type may be used with amp-embed tag.
  * @const {!Object<string, boolean>}
@@ -396,57 +403,23 @@ function isMaster() {
 window.draw3p = function(opt_configCallback, opt_allowed3pTypes,
     opt_allowedEmbeddingOrigins) {
   try {
+    const location = parseUrl(data._context.location.href);
+
     ensureFramed(window);
-    window.context.location = parseUrl(data._context.location.href);
-    validateParentOrigin(window, window.context.location);
+    validateParentOrigin(window, location);
     validateAllowedTypes(window, data.type, opt_allowed3pTypes);
     if (opt_allowedEmbeddingOrigins) {
       validateAllowedEmbeddingOrigins(window, opt_allowedEmbeddingOrigins);
     }
-    // Define master related properties to be lazily read.
-    Object.defineProperties(window.context, {
-      master: {
-        get: () => masterSelection(data.type),
-      },
-      isMaster: {
-        get: isMaster,
-      },
-    });
-    window.context.data = data;
-    window.context.noContentAvailable = triggerNoContentAvailable;
-    window.context.requestResize = triggerResizeRequest;
-    window.context.renderStart = triggerRenderStart;
-
-    if (data.type === 'facebook' || data.type === 'twitter') {
-      // Only make this available to selected embeds until the
-      // generic solution is available.
-      window.context.updateDimensions = triggerDimensions;
-    }
-
-    // This only actually works for ads.
-    const initialIntersection = window.context.initialIntersection;
-    window.context.observeIntersection = cb => {
-      const unlisten = observeIntersection(cb);
-      // Call the callback with the value that was transmitted when the
-      // iframe was drawn. Called in nextTick, so that callers don't
-      // have to specially handle the sync case.
-      nextTick(window, () => cb([initialIntersection]));
-      return unlisten;
-    };
-    window.context.onResizeSuccess = onResizeSuccess;
-    window.context.onResizeDenied = onResizeDenied;
-    window.context.reportRenderedEntityIdentifier =
-        reportRenderedEntityIdentifier;
-    window.context.computeInMasterFrame = computeInMasterFrame;
-    window.context.addContextToIframe = iframe => {
-      iframe.name = iframeName;
-    };
-    window.context.getHtml = getHtml;
+    installContext(window);
     delete data._context;
     manageWin(window);
     installEmbedStateListener();
     draw3p(window, data, opt_configCallback);
     updateVisibilityState(window);
+
+    // TODO(alanorozco): use IframeMessagingClient for updates when experiment
+    //                   flag is on.
     // Subscribe to page visibility updates.
     nonSensitiveDataPostMessage('send-embed-state');
     nonSensitiveDataPostMessage('bootstrap-loaded');
@@ -459,6 +432,60 @@ window.draw3p = function(opt_configCallback, opt_allowed3pTypes,
   }
 };
 
+function installContext(win) {
+  if (isExperimentOn(win, AMP_CONTEXT_EXPERIMENT)) {
+    // TODO(alanorozco): Enhance AmpContext to match standard implementation.
+    win.context = new AmpContext(win);
+    return;
+  }
+
+  installContextUsingStandardImpl(win);
+}
+
+function installContextUsingStandardImpl(win) {
+  // Define master related properties to be lazily read.
+  Object.defineProperties(win.context, {
+    master: {
+      get: () => masterSelection(data.type),
+    },
+    isMaster: {
+      get: isMaster,
+    },
+  });
+
+  win.context.data = data;
+  win.context.location = data._context.location;
+  win.context.noContentAvailable = triggerNoContentAvailable;
+  win.context.requestResize = triggerResizeRequest;
+  win.context.renderStart = triggerRenderStart;
+
+  if (data.type === 'facebook' || data.type === 'twitter') {
+    // Only make this available to selected embeds until the
+    // generic solution is available.
+    win.context.updateDimensions = triggerDimensions;
+  }
+
+  // This only actually works for ads.
+  const initialIntersection = win.context.initialIntersection;
+  win.context.observeIntersection = cb => {
+    const unlisten = observeIntersection(cb);
+    // Call the callback with the value that was transmitted when the
+    // iframe was drawn. Called in nextTick, so that callers don't
+    // have to specially handle the sync case.
+    nextTick(win, () => cb([initialIntersection]));
+    return unlisten;
+  };
+  win.context.onResizeSuccess = onResizeSuccess;
+  win.context.onResizeDenied = onResizeDenied;
+  win.context.reportRenderedEntityIdentifier =
+      reportRenderedEntityIdentifier;
+  win.context.computeInMasterFrame = computeInMasterFrame;
+  win.context.addContextToIframe = iframe => {
+    iframe.name = iframeName;
+  };
+  win.context.getHtml = getHtml;
+}
+
 function triggerNoContentAvailable() {
   nonSensitiveDataPostMessage('no-content');
 }

tools/experiments/experiments.js

@@ -266,6 +266,12 @@ const EXPERIMENTS = [
     cleanupIssue: 'https://github.com/ampproject/amphtml/issues/8195',
     spec: 'https://github.com/ampproject/amphtml/issues/7670',
   },
+  {
+    id: '3p-use-ampcontext',
+    name: 'Use AmpContext for window.context messaging',
+    cleanupIssue: 'https://github.com/ampproject/amphtml/issues/8239',
+    spec: 'https://github.com/ampproject/amphtml/issues/6829',
+  },
 ];
 
 if (getMode().localDev) {