recipes: Add a GN flavor.

infra/bots/recipe_modules/skia/gn_flavor.py

+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import default_flavor
+
+"""GN flavor utils, used for building Skia with GN."""
+class GNFlavorUtils(default_flavor.DefaultFlavorUtils):
+  def compile(self, target):
+    """Build Skia with GN."""
+    # Get the gn executable.
+    fetch_gn = self._skia_api.skia_dir.join('bin', 'fetch-gn')
+    self._skia_api.run(self._skia_api.m.step, 'fetch-gn', cmd=[fetch_gn],
+                       cwd=self._skia_api.skia_dir)
+
+    is_debug = 'is_debug=true'
+    if self._skia_api.configuration != 'Debug':
+        is_debug = 'is_debug=false'
+    gn_args = [is_debug]
+
+    # Run gn gen.
+    gn_exe = 'gn'
+    if self._skia_api.m.platform.is_win:
+        gn_exe = 'gn.exe'
+    gn_gen = [gn_exe, 'gen', self.out_dir, '--args=%s' % ' '.join(gn_args)]
+    self._skia_api.run(self._skia_api.m.step, 'gn_gen', cmd=gn_gen,
+                       cwd=self._skia_api.skia_dir)
+
+    # Run ninja.
+    ninja_cmd = ['ninja', '-C', self.out_dir]
+    self._skia_api.run(self._skia_api.m.step, 'compile %s' % target,
+            cmd=ninja_cmd,
+            cwd=self._skia_api.skia_dir)