Use gyp targets to link in X11 libraries instead of setting -lXfoo

ui/ui.gyp

Index: ui/ui.gyp
diff --git a/ui/ui.gyp b/ui/ui.gyp
index 28148e396387adbdb507251519faf824d1e84e37..e731809d341d1d81876247dc3d712411b9f307af 100644
--- a/ui/ui.gyp
+++ b/ui/ui.gyp
@@ -527,25 +527,23 @@
             'ldflags': [
               '-L<(PRODUCT_DIR)',
             ],
+            # TODO(jamesr): Targets using X11 should declare dependencies on the
+            # appropriate build/linux/system.gyp targets themselves instead of
+            # independently picking it up from ui.
             'link_settings': {
               'libraries': [
                 '-lX11',
                 '-lXcursor',
-                '-lXrender',  # For XRender* function calls in x11_util.cc.
+                '-lXrender',

[piman, 2014/02/04 00:25:14]

nit: won't all these be inherited now, since they're in dependencies?

[jamesr, 2014/02/04 00:27:14]

Without this all_dependent_settings entries many targets (mostly unit tests)
that link against libui.so but do not declare a dependency directly on
ui/ui.gyp:ui do not have the -lXrender/etc lines on their final link lines and
thus fail to link.  I think the right fix is for these targets to either declare
dependencies on ui.gyp:ui or (if they use X11 directly) on the relevant X11
targets, but I haven't chased them all down yet.

               ],
             },
           },
-          'link_settings': {
-            'libraries': [
-              '-lX11',
-              '-lXcursor',
-              '-lXrender',  # For XRender* function calls in x11_util.cc.
-            ],
-          },
           'dependencies': [
             '../build/linux/system.gyp:x11',
+            '../build/linux/system.gyp:xcursor',
             '../build/linux/system.gyp:xext',
             '../build/linux/system.gyp:xfixes',
+            '../build/linux/system.gyp:xrender',  # For XRender* function calls in x11_util.cc.
           ],
         }],
         ['use_ozone==0', {