Bug 1697928 - Select process for about:reader based on article URI, r=annyG

Differential Revision: https://phabricator.services.mozilla.com/D108864

toolkit/components/reader/test/browser.ini

@@ -41,3 +41,6 @@ support-files =
   readerModeArticle.html
   readerModeArticleShort.html
   readerModeArticleMedium.html
+[browser_readerMode_remoteType.js]
+support-files =
+  readerModeArticleShort.html

toolkit/components/reader/test/browser_readerMode_remoteType.js

@@ -0,0 +1,87 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const TEST_PATH = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  "http://example.com"
+);
+
+const CROSS_SITE_TEST_PATH = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  "http://example.org"
+);
+
+/**
+ * Test that switching an article into readermode doesn't change its' remoteType.
+ * Test that the reader mode correctly calculates and displays the
+ * estimated reading time for a short article
+ */
+add_task(async function() {
+  info("opening readermode normally to ensure process doesn't change");
+  let articleRemoteType;
+  let aboutReaderURL;
+  await BrowserTestUtils.withNewTab(
+    TEST_PATH + "readerModeArticleShort.html",
+    async function(browser) {
+      articleRemoteType = browser.remoteType;
+
+      // Click on the readermode button to switch into reader mode, and get the
+      // URL for that reader mode.
+      let pageShownPromise = BrowserTestUtils.waitForContentEvent(
+        browser,
+        "AboutReaderContentReady"
+      );
+      let readerButton = document.getElementById("reader-mode-button");
+      readerButton.click();
+      await pageShownPromise;
+
+      aboutReaderURL = browser.documentURI.spec;
+      ok(
+        aboutReaderURL.startsWith("about:reader"),
+        "about:reader should have been opened"
+      );
+      is(
+        browser.remoteType,
+        articleRemoteType,
+        "remote type should not have changed"
+      );
+    }
+  );
+
+  info(
+    "opening new tab directly with about reader URL into correct remote type"
+  );
+  await BrowserTestUtils.withNewTab(aboutReaderURL, async function(browser) {
+    is(
+      browser.remoteType,
+      articleRemoteType,
+      "Should have performed about:reader load in the correct remote type"
+    );
+  });
+
+  info("navigating process into correct remote type");
+  await BrowserTestUtils.withNewTab(
+    CROSS_SITE_TEST_PATH + "readerModeArticleShort.html",
+    async function(browser) {
+      if (SpecialPowers.useRemoteSubframes) {
+        isnot(
+          browser.remoteType,
+          articleRemoteType,
+          "Cross-site article should have different remote type with fission"
+        );
+      }
+
+      BrowserTestUtils.loadURI(browser, aboutReaderURL);
+      await BrowserTestUtils.browserLoaded(browser);
+
+      is(
+        browser.remoteType,
+        articleRemoteType,
+        "Should have switched into the correct remote type"
+      );
+    }
+  );
+});

toolkit/modules/E10SUtils.jsm

@@ -82,6 +82,16 @@ function getAboutModule(aURL) {
   }
 }
 
+function getOriginalReaderModeURI(aURI) {
+  try {
+    let searchParams = new URLSearchParams(aURI.query);
+    if (searchParams.has("url")) {
+      return Services.io.newURI(searchParams.get("url"));
+    }
+  } catch (e) {}
+  return null;
+}
+
 const NOT_REMOTE = null;
 
 // These must match any similar ones in ContentParent.h and ProcInfo.h
@@ -474,6 +484,32 @@ var E10SUtils = {
           ) {
             return PRIVILEGEDABOUT_REMOTE_TYPE;
           }
+
+          // When loading about:reader, try to display the document in the same
+          // web remote type as the document it's loading.
+          if (aURI.filePath == "reader") {
+            let readerModeURI = getOriginalReaderModeURI(aURI);
+            if (readerModeURI) {
+              let innerRemoteType = this.getRemoteTypeForURIObject(
+                readerModeURI,
+                aMultiProcess,
+                aRemoteSubframes,
+                aPreferredRemoteType,
+                aCurrentUri,
+                null, // aResultPrincipal
+                aIsSubframe,
+                aIsWorker,
+                aOriginAttributes
+              );
+              if (
+                innerRemoteType &&
+                innerRemoteType.startsWith(WEB_REMOTE_TYPE)
+              ) {
+                return innerRemoteType;
+              }
+            }
+          }
+
           return DEFAULT_REMOTE_TYPE;
         }