aura: Make 'ui' buildable without gtk.

ui/gfx/rect.cc

Index: ui/gfx/rect.cc
diff --git a/ui/gfx/rect.cc b/ui/gfx/rect.cc
index 96a8b0dc2ed54a28a9758486224a3bbff06deaf4..ee557d76ce9133959c2f6d3c1bb677d2f0966b18 100644
--- a/ui/gfx/rect.cc
+++ b/ui/gfx/rect.cc
@@ -8,7 +8,7 @@
 #include <windows.h>
 #elif defined(OS_MACOSX)
 #include <CoreGraphics/CGGeometry.h>
-#elif defined(USE_X11)
+#elif defined(TOOLKIT_USES_GTK)
 #include <gdk/gdk.h>
 #endif
 #if defined(USE_WAYLAND)
@@ -80,7 +80,7 @@ Rect& Rect::operator=(const CGRect& r) {
   set_height(r.size.height);
   return *this;
 }
-#elif defined(USE_X11)
+#elif defined(TOOLKIT_USES_GTK)
 Rect::Rect(const GdkRectangle& r)
     : origin_(r.x, r.y) {
   set_width(r.width);
@@ -159,7 +159,7 @@ RECT Rect::ToRECT() const {
 CGRect Rect::ToCGRect() const {
   return CGRectMake(x(), y(), width(), height());
 }
-#elif defined(USE_X11)
+#elif defined(TOOLKIT_USES_GTK)
 GdkRectangle Rect::ToGdkRectangle() const {
   GdkRectangle r = {x(), y(), width(), height()};
   return r;