Files.app: Use the same file type associates as Windows on HTML files.

This CL associates .xhtm, .xhtml, and .shtml to the browser window.
The list matches what Chrome handles on Windows, enumerated at
src/chrome/installer/util/shell_util.cc#kDefaultFileAssociations.

BUG=427542

Review URL: https://codereview.chromium.org/693103003

Cr-Commit-Position: refs/heads/master@{#302235}

chrome/browser/chromeos/file_manager/open_with_browser.cc

@@ -52,6 +52,9 @@ const base::FilePath::CharType* kFileExtensionsViewableInBrowser[] = {
   FILE_PATH_LITERAL(".htm"),
   FILE_PATH_LITERAL(".mhtml"),
   FILE_PATH_LITERAL(".mht"),
+  FILE_PATH_LITERAL(".xhtml"),
+  FILE_PATH_LITERAL(".xht"),
+  FILE_PATH_LITERAL(".shtml"),
   FILE_PATH_LITERAL(".svg"),
 };
 

ui/file_manager/file_manager/foreground/js/file_type.js

@@ -163,7 +163,7 @@ FileType.types = [
   },
   {
     type: 'document', name: 'HTML_DOCUMENT_FILE_TYPE',
-    subtype: 'HTML', pattern: /\.(html?|mht|mhtml)$/i
+    subtype: 'HTML', pattern: /\.(html?|mht(ml)?|shtml|xht(ml)?)$/i
   },
   {
     type: 'document', icon: 'word', name: 'WORD_DOCUMENT_FILE_TYPE',

ui/file_manager/file_manager/manifest.json

@@ -75,6 +75,9 @@
         "filesystem:*.html",
         "filesystem:*.mht",
         "filesystem:*.mhtml",
+        "filesystem:*.shtml",
+        "filesystem:*.xht",
+        "filesystem:*.xhtml",
         "filesystem:*.svg",
         "filesystem:*.txt"
       ]