Re-add backspace-goes-back as a default disabled finch trial

chrome/browser/global_keyboard_shortcuts_mac_unittest.mm

Index: chrome/browser/global_keyboard_shortcuts_mac_unittest.mm
diff --git a/chrome/browser/global_keyboard_shortcuts_mac_unittest.mm b/chrome/browser/global_keyboard_shortcuts_mac_unittest.mm
index 2359d8a881fd668b458ef4242e6bd9a47856bccc..df0e4ebe0d67c6df30db2bdf563051e4ae51158e 100644
--- a/chrome/browser/global_keyboard_shortcuts_mac_unittest.mm
+++ b/chrome/browser/global_keyboard_shortcuts_mac_unittest.mm
@@ -29,11 +29,13 @@ TEST(GlobalKeyboardShortcuts, ShortcutsToWindowCommand) {
     EXPECT_EQ(cmd_num, it->chrome_command);
   }
 
-  // Test that cmd-left is not a window-level command (else it
-  // would be invoked even if e.g. the omnibox had focus, where it really
+  // Test that cmd-left and backspace are not window-level commands (else they
+  // would be invoked even if e.g. the omnibox had focus, where they really
   // should have text editing functionality).
   EXPECT_EQ(-1, CommandForWindowKeyboardShortcut(
       true, false, false, false, kVK_LeftArrow, 0));
+  EXPECT_EQ(-1, CommandForWindowKeyboardShortcut(
+      false, false, false, false, kVK_Delete, 0));
 
   // Test that Cmd-'{' and Cmd-'}' are interpreted as IDC_SELECT_NEXT_TAB
   // and IDC_SELECT_PREVIOUS_TAB regardless of the virtual key code values.