Make the gyp files more cross-platform across the Unices

ui/gfx/gl/gl.gyp

Index: ui/gfx/gl/gl.gyp
diff --git a/ui/gfx/gl/gl.gyp b/ui/gfx/gl/gl.gyp
index 83acee44f9592d3bbc1c00304734f3e407f3e63f..683416d6e88b4be2726d8dc8487fc7fe471d6c5b 100644
--- a/ui/gfx/gl/gl.gyp
+++ b/ui/gfx/gl/gl.gyp
@@ -10,7 +10,7 @@
       ['exclude', '/(gtk|win|x11)_[^/]*\\.cc$'],
     ],
     'conditions': [
-      ['OS=="linux" or OS=="freebsd" or OS=="openbsd"', {'sources/': [
+      ['toolkit_uses_gtk==1', {'sources/': [
         ['include', '/gtk/'],
         ['include', '_(gtk|linux|posix|skia|x)\\.cc$'],
         ['include', '/(gtk|x11)_[^/]*\\.cc$'],
@@ -123,7 +123,7 @@
         },
       ],
       'conditions': [
-        ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="win"', {
+        ['(os_posix==1 and OS!="mac") or OS=="win"', {
           'sources': [
             'egl_util.cc',
             'egl_util.h',
@@ -138,7 +138,7 @@
             '<(DEPTH)/third_party/angle/include',
           ],
         }],
-        ['OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
+        ['use_x11==1', {
           'sources': [
             'gl_context_glx.cc',
             'gl_context_glx.h',