Remove libgtk3ui from gn_all

chrome/browser/ui/libgtkui/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 assert(is_linux, "This file should only be referenced on Linux")
 
 import("//build/config/features.gni")
 import("//build/config/linux/gtk/gtk.gni")
 import("//printing/features/features.gni")
 
@@ skipping 122 matching lines @@
              "//ui/shell_dialogs",
              "//ui/strings",
              "//ui/views",
            ]
     public_deps = [
       "//chrome/browser:theme_properties",
     ]
   }
 }
 
-libgtkui("libgtk2ui") {
-  sources = [
-    "native_theme_gtk2.cc",
-    "native_theme_gtk2.h",
-  ]
-  deps = [
-    "//build/config/linux/gtk2",
-    "//build/config/linux/gtk2:gtkprint2",
-  ]
+if (use_gtk3) {
+  libgtkui("libgtk3ui") {
+    sources = [
+      "native_theme_gtk3.cc",
+      "native_theme_gtk3.h",
+    ]
+    deps = [
+      "//build/config/linux/gtk3",
+      "//build/config/linux/gtk3:gtkprint3",
+    ]
+  }
+} else {
+  libgtkui("libgtk2ui") {
+    sources = [
+      "native_theme_gtk2.cc",
+      "native_theme_gtk2.h",
+    ]
+    deps = [
+      "//build/config/linux/gtk2",
+      "//build/config/linux/gtk2:gtkprint2",
+    ]
+  }
 }
-
-# This is compiled with "all" even when it's not referenced to ensure that
-# GTK3 continues to build. GTK3 is explicitly specified by some distros.
-libgtkui("libgtk3ui") {
-  sources = [
-    "native_theme_gtk3.cc",
-    "native_theme_gtk3.h",
-  ]
-  deps = [
-    "//build/config/linux/gtk3",
-    "//build/config/linux/gtk3:gtkprint3",
-  ]
-}