Add config options to run different GPU APIs to dm and nanobench

gyp/flags.gyp

Index: gyp/flags.gyp
diff --git a/gyp/flags.gyp b/gyp/flags.gyp
index 0fd52b375b18c9c5e69bfcd88c5cf4a0ef1ec2b5..769a7bdb57721d1b35e212b7b41335c52006ae38 100644
--- a/gyp/flags.gyp
+++ b/gyp/flags.gyp
@@ -29,9 +29,15 @@
     {
       'target_name': 'flags_common',
       'type': 'static_library',
+      'include_dirs': [
+          '../include/gpu',
+          '../src/gpu',
+      ],
       'sources': [
         '../tools/flags/SkCommonFlags.cpp',
         '../tools/flags/SkCommonFlags.h',
+        '../tools/flags/SkCommonFlagsConfig.cpp',
+        '../tools/flags/SkCommonFlagsConfig.h',
       ],
       'dependencies': [
         'skia_lib.gyp:skia_lib',
@@ -39,6 +45,8 @@
       ],
       'direct_dependent_settings': {
         'include_dirs': [
+          '../include/gpu',
+          '../src/gpu',
           '../tools/flags',
         ],
       }