Do not toggle the recent browser before showing disambiguation menu

Currently if the Chrome icon is clicked while there are multiple
browser windows (or multiple tabs when clicked with Shift), the most
recently active browser window will be activated, then the
disambiguation menu will be shown. This startles the user, especially
if the browser window was previously minimized.
This CL prevents this from happening.

Bug: 926980
Test: manual
Change-Id: Ia86f9eb43c589928b22e9556e3c4c97abc194837
Reviewed-on: https://chromium-review.googlesource.com/c/1449104Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Yury Khmel <khmel@chromium.org>
Commit-Queue: Vladislav Kaznacheev <kaznacheev@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628229}

chrome/browser/ui/ash/launcher/browser_shortcut_launcher_item_controller.cc

@@ -255,9 +255,16 @@ void BrowserShortcutLauncherItemController::ItemSelected(
     return;
   }
 
-  ash::ShelfAction action =
-      ChromeLauncherController::instance()->ActivateWindowOrMinimizeIfActive(
-          last_browser->window(), items.size() == 1);
+  ash::ShelfAction action;
+  if (items.size() == 1) {
+    action =
+        ChromeLauncherController::instance()->ActivateWindowOrMinimizeIfActive(
+            last_browser->window(), true);
+  } else {
+    // Multiple targets, a menu will be shown. No need to activate or minimize
+    // the recently active browser.
+    action = ash::SHELF_ACTION_NONE;
+  }
   std::move(callback).Run(action, std::move(items));
 }