[Closure Externs] Generate closure compiler externs as part of compile

third_party/closure_compiler/externs/compiled_resources2.gyp

Index: third_party/closure_compiler/externs/compiled_resources2.gyp
diff --git a/third_party/closure_compiler/externs/compiled_resources2.gyp b/third_party/closure_compiler/externs/compiled_resources2.gyp
index 488f6deb5029daaadb6789d6a3d76026e48fb578..933769d88af1882e3170d8338cf228d13c724429 100644
--- a/third_party/closure_compiler/externs/compiled_resources2.gyp
+++ b/third_party/closure_compiler/externs/compiled_resources2.gyp
@@ -45,7 +45,7 @@
       'includes': ['../include_js.gypi'],
     },
     {
-      'target_name': 'developer_private',
+      'target_name': '../../../out/gnd/gen/third_party/closure_compiler/externs/developer_private',

[Devlin, 2016/12/15 18:56:40]

This is obviously wrong. :)  How should this be?

[Dan Beam, 2016/12/16 05:39:52]

it's hard to say exactly how GYP and GN should share this info (or if they
should).

if closure was GN, it would be easier.

it's possible that something like SHARED_INTERMEDIATE_DIR might work, but I'm
worried
https://gyp.gsrc.io/docs/InputFormatReference.md#Predefined-Variables

we could also just generate to somewhere in src/ and add the generated files to
.gitignore... but all of these are less nice than sharing GN between both
systems

[Dirk Pranke, 2017/01/09 05:20:02]

We shouldn't generate things into src/. I'm not sure if SHARED_INTERMEDIATE_DIR
will work, but it's worth trying. Otherwise I'd be fine w/ just getting some
hack working until we can move to GN.

       'includes': ['../include_js.gypi'],
     },
     {