mac: Restore the "Hide Other" main menu shortcut.

Also ensure Hide Others and Show All are in the PWA menus.

Bug: 892480
Change-Id: I507771745c95203fda8344703c7b1b015a93699a
Reviewed-on: https://chromium-review.googlesource.com/c/1288851Reviewed-by: ccameron <ccameron@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600851}

chrome/browser/ui/cocoa/main_menu_builder.mm

@@ -55,10 +55,10 @@ base::scoped_nsobject<NSMenuItem> BuildAppMenu(
                     .action(@selector(hide:)),
                 Item(IDS_HIDE_OTHERS_MAC)
                     .action(@selector(hideOtherApplications:))
-                    .remove_if(is_pwa),
+                    .key_equivalent(@"h", NSEventModifierFlagCommand |
+                                              NSEventModifierFlagOption),
                 Item(IDS_SHOW_ALL_MAC)
-                    .action(@selector(unhideAllApplications:))
-                    .remove_if(is_pwa),
+                    .action(@selector(unhideAllApplications:)),
                 Item().is_separator(),
                 Item(IDS_CONFIRM_TO_QUIT_OPTION)
                     .target(app_delegate)