[quickview] Add test for display of MHTML files

Bug: 960277
Tests: browser_tests --gtest_filter="*openQuickViewMhtml*"
Change-Id: I8be8483e6b5dd6e3e99701bfc14551262c782090
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2131822Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Alex Danilo <adanilo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756052}

chrome/browser/chromeos/file_manager/file_manager_browsertest.cc

@@ -499,6 +499,7 @@ WRAPPED_INSTANTIATE_TEST_SUITE_P(
         TestCase("openQuickViewSniffedText"),
         TestCase("openQuickViewScrollText"),
         TestCase("openQuickViewScrollHtml"),
+        TestCase("openQuickViewMhtml"),
         TestCase("openQuickViewBackgroundColorHtml"),
         TestCase("openQuickViewDrive"),
         TestCase("openQuickViewSmbfs").EnableSmbfs(),

chrome/test/data/chromeos/file_manager/page.mhtml

+From: <Saved by Blink>
+Subject: 
+Date: Fri, 24 May 2019 00:27:44 -0000
+MIME-Version: 1.0
+Content-Type: multipart/related;
+	type="text/html";
+	boundary="----MultipartBoundary--VKh1aJ3tgkQhPUVQ6JkAhXAQyIRNSPLAzGo7YI6gjP----"
+
+------MultipartBoundary--VKh1aJ3tgkQhPUVQ6JkAhXAQyIRNSPLAzGo7YI6gjP----
+Content-Type: text/plain
+
+Hello World
+------MultipartBoundary--VKh1aJ3tgkQhPUVQ6JkAhXAQyIRNSPLAzGo7YI6gjP------

ui/file_manager/integration_tests/file_manager/quick_view.js

@@ -725,6 +725,42 @@
     chrome.test.assertEq('application/pdf', mimeType);
   };
 
+  /**
+   * Tests opening Quick View with a '.mhtml' filename extension.
+   */
+  testcase.openQuickViewMhtml = async () => {
+    const caller = getCaller();
+
+    /**
+     * The text <webview> resides in the #quick-view shadow DOM, as a child of
+     * the #dialog element.
+     */
+    const webView = ['#quick-view', 'files-safe-media[type="html"]', 'webview'];
+
+    // Open Files app on Downloads containing ENTRIES.plainText.
+    const appId =
+        await setupAndWaitUntilReady(RootPath.DOWNLOADS, [ENTRIES.mHtml], []);
+
+    // Open the file in Quick View.
+    await openQuickView(appId, ENTRIES.mHtml.nameText);
+
+    // Wait for the Quick View <webview> to load and display its content.
+    function checkWebViewTextLoaded(elements) {
+      let haveElements = Array.isArray(elements) && elements.length === 1;
+      if (haveElements) {
+        haveElements = elements[0].styles.display.includes('block');
+      }
+      if (!haveElements || !elements[0].attributes.src) {
+        return pending(caller, 'Waiting for <webview> to load.');
+      }
+      return;
+    }
+    await repeatUntil(async () => {
+      return checkWebViewTextLoaded(await remoteCall.callRemoteTestUtil(
+          'deepQueryAllElements', appId, [webView, ['display']]));
+    });
+  };
+
   /**
    * Tests opening Quick View and scrolling its <webview> which contains a tall
    * html document.

ui/file_manager/integration_tests/test_util.js

@@ -712,6 +712,17 @@ const ENTRIES = {
     typeText: 'Plain text',
   }),
 
+  mHtml: new TestEntryInfo({
+    type: EntryType.FILE,
+    sourceFileName: 'page.mhtml',
+    targetPath: 'page.mhtml',
+    mimeType: 'multipart/related',
+    lastModifiedTime: 'Sep 4, 1998, 12:34 PM',
+    nameText: 'page.mhtml',
+    sizeText: '421 bytes',
+    typeText: 'HTML document',
+  }),
+
   tallHtml: new TestEntryInfo({
     type: EntryType.FILE,
     sourceFileName: 'tall.html',