Export the dependency of infobars on skia in gyp

This dependency is already exported in BUILD.gn, but not in infobars.gypi.

Infobar code transitively includes skia headers.
An example of this is infobars.h including SkColor.h.
These skia headers need skia to be added in the include path in order to
compile.
Because of this, any target depending on infobars must also add skia
include dirs.

Review URL: https://codereview.chromium.org/650203002

Cr-Commit-Position: refs/heads/master@{#299330}

components/infobars.gypi

@@ -17,6 +17,9 @@
         '../ui/gfx/gfx.gyp:gfx',
         '../ui/strings/ui_strings.gyp:ui_strings',
       ],
+      'export_dependent_settings': [
+        '../skia/skia.gyp:skia',
+      ],
       'sources': [
         # Note: sources duplicated in GN build.
         'infobars/core/confirm_infobar_delegate.cc',