[Reading List] Navigate to the amphtml link in Google SRP AMP pages.

ios/chrome/browser/reading_list/reading_list_distiller_page.mm

 // Copyright 2016 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 "ios/chrome/browser/reading_list/reading_list_distiller_page.h"
 
 #include "base/bind.h"
 #include "base/mac/foundation_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/favicon/ios/web_favicon_driver.h"
 #include "components/google/core/browser/google_util.h"
 #include "ios/chrome/browser/reading_list/favicon_web_state_dispatcher_impl.h"
 #import "ios/web/public/navigation_item.h"
 #import "ios/web/public/navigation_manager.h"
 #include "ios/web/public/ssl_status.h"
 #import "ios/web/public/web_state/js/crw_js_injection_receiver.h"
 #import "ios/web/public/web_state/web_state.h"
 #import "net/base/mac/url_conversions.h"
 #include "net/cert/cert_status_flags.h"
 #include "url/url_constants.h"
 
 namespace {
 // The delay given to the web page to render after the PageLoaded callback.
 const int64_t kPageLoadDelayInSeconds = 2;
 
+// This script retrieve the href parameter of the <link rel="amphtml"> element
+// of the page if it exists. If it does not exist, it returns the src of the
+// first iframe of the page.
 const char* kGetIframeURLJavaScript =
-    "document.getElementsByTagName('iframe')[0].src;";
+    "(() => {"
+    "  var link = document.evaluate('//link[@rel=\"amphtml\"]',"
+    "                               document,"
+    "                               null,"
+    "                               XPathResult.ORDERED_NODE_SNAPSHOT_TYPE,"
+    "                               null ).snapshotItem(0);"
+    "  if (link !== null) {"
+    "    return link.getAttribute('href');"
+    "  }"
+    "  return document.getElementsByTagName('iframe')[0].src;"
+    "})()";
 }  // namespace
 
 namespace reading_list {
 
 ReadingListDistillerPageDelegate::ReadingListDistillerPageDelegate() {}
 ReadingListDistillerPageDelegate::~ReadingListDistillerPageDelegate() {}
 
 ReadingListDistillerPage::ReadingListDistillerPage(
     web::BrowserState* browser_state,
     FaviconWebStateDispatcher* web_state_dispatcher,
@@ skipping 163 matching lines @@
     id result,
     id error) {
   if (error) {
     return false;
   }
   NSString* result_string = base::mac::ObjCCast<NSString>(result);
   NSURL* new_url = [NSURL URLWithString:result_string];
   if (!new_url) {
     return false;
   }
-  bool is_cdn_ampproject =
-      [[new_url host] isEqualToString:@"cdn.ampproject.org"];
-  bool is_cdn_ampproject_subdomain =
-      [[new_url host] hasSuffix:@".cdn.ampproject.org"];
 
-  if (!is_cdn_ampproject && !is_cdn_ampproject_subdomain) {
-    return false;
-  }
   GURL new_gurl = net::GURLWithNSURL(new_url);
   if (!new_gurl.is_valid()) {
     return false;
   }
   FetchFavicon(new_gurl);
   web::NavigationManager::WebLoadParams params(new_gurl);
   CurrentWebState()->GetNavigationManager()->LoadURLWithParams(params);
   return true;
 }
 
 }  // namespace reading_list