Remove libgtk3ui from gn_all

chrome/browser/ui/libgtkui/BUILD.gn

Index: chrome/browser/ui/libgtkui/BUILD.gn
diff --git a/chrome/browser/ui/libgtkui/BUILD.gn b/chrome/browser/ui/libgtkui/BUILD.gn
index 849f28906a3c561103b951b8e2432e6374879419..9b50cbca2bbf6472eaed1486c93f6ac344cc514d 100644
--- a/chrome/browser/ui/libgtkui/BUILD.gn
+++ b/chrome/browser/ui/libgtkui/BUILD.gn
@@ -140,26 +140,26 @@ template("libgtkui") {
   }
 }
 
-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",
-  ]
+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",
+    ]
+  }
 }