Tab Search: put keyboard shortcut under feature flag on Mac

This CL makes Tab Search shortcut (cmd+shift+A) available
when the Tab Search feature flag is off.

Bug: 1099917, 1153526
Change-Id: Ic5ba4e16cd458f4f0e5541a852435bd07ada610e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2568151Reviewed-by: Thomas Lukaszewicz <tluk@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Yuheng Huang <yuhengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832572}

chrome/browser/global_keyboard_shortcuts_mac.mm

@@ -16,6 +16,7 @@
 #import "chrome/browser/app_controller_mac.h"
 #include "chrome/browser/ui/cocoa/accelerators_cocoa.h"
 #import "chrome/browser/ui/cocoa/nsmenuitem_additions.h"
+#include "chrome/browser/ui/ui_features.h"
 #include "ui/base/accelerators/accelerator.h"
 #include "ui/base/accelerators/platform_accelerator_cocoa.h"
 #include "ui/events/event_constants.h"
@@ -166,11 +167,13 @@ const std::vector<KeyboardShortcutData>& GetShortcutsNotPresentInMainMenu() {
     {true,  false, false, true,  kVK_ANSI_L,            IDC_SHOW_DOWNLOADS},
     {true,  true,  false, false, kVK_ANSI_C,            IDC_DEV_TOOLS_INSPECT},
     {true,  false, false, true,  kVK_ANSI_C,            IDC_DEV_TOOLS_INSPECT},
-    {true,  true,  false, false, kVK_ANSI_A,            IDC_TAB_SEARCH},
 
     {true,  false, false, true,  kVK_DownArrow,         IDC_FOCUS_NEXT_PANE},
     {true,  false, false, true,  kVK_UpArrow,           IDC_FOCUS_PREVIOUS_PANE},
   });
+  if (base::FeatureList::IsEnabled(features::kTabSearch)) {
+    keys->push_back({true,  true,  false, false, kVK_ANSI_A, IDC_TAB_SEARCH});
+  }
   // clang-format on
   return *keys;
 }