Move mac_views_browser grit define out of tools/grit.

tools/grit/grit_rule.gni

Index: tools/grit/grit_rule.gni
diff --git a/tools/grit/grit_rule.gni b/tools/grit/grit_rule.gni
index 52c6d53814cff3a5aabc3241d6003fa20bc2f909..e9e497d98141b6907673086c74c7fd65d0dd14a9 100644
--- a/tools/grit/grit_rule.gni
+++ b/tools/grit/grit_rule.gni
@@ -92,7 +92,6 @@ import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//third_party/closure_compiler/closure_args.gni")
-import("//ui/base/ui_features.gni")
 
 assert(!enable_resource_whitelist_generation || is_android,
        "resource whitelist generation only works on android")
@@ -259,12 +258,6 @@ if (enable_notifications) {
     "enable_notifications",
   ]
 }
-if (mac_views_browser) {
-  grit_defines += [
-    "-D",
-    "mac_views_browser",
-  ]
-}
 
 # TODO(aberent): Enable for other platforms once the build machines have
 #                Java on them (and hence can run the closure compiler).