Turn //mojo/public/cpp/bindings and //mojo/public/cpp/system into components

mojo/public/tools/bindings/mojom.gni

Index: mojo/public/tools/bindings/mojom.gni
diff --git a/mojo/public/tools/bindings/mojom.gni b/mojo/public/tools/bindings/mojom.gni
index be36cb49d6200e1ea6742b1bceeb4a5bcbd6aba6..757e06efb07ddc62b41aa28ec3ce358050db1ce9 100644
--- a/mojo/public/tools/bindings/mojom.gni
+++ b/mojo/public/tools/bindings/mojom.gni
@@ -204,6 +204,10 @@ template("mojom") {
       full_name = get_label_info("$d", "label_no_toolchain")
       public_deps += [ "${full_name}_${shared_cpp_sources_suffix}" ]
     }
+    defines = []
+    if (defined(invoker.export_define)) {
+      defines += [ invoker.export_define ]

[yzshen1, 2016/09/22 18:26:27]

Why this is needed?

[yzshen1, 2016/09/22 18:34:10]

Just saw your comments. Let me think about it some more...

[yzshen1, 2016/09/22 19:39:36]

It seems a little hacky because invoker.export_define is for the "chromium
variant" while this shared_cpp_sources is used by both the "chromium variant"
and "blink variant". 

I think another possible solution is to make mojo/public/cpp/bindings depends on
mojo/public/interfaces/bindings:bindings__generator (which just generates
files), and then explicitly adds those generated files into the sources section
of mojo/public/cpp/bindings.
Because this is a very special case, I think maybe it is fine to be verbose.

WDYT? Thanks!

[dcheng, 2016/09/22 22:18:21]

It's very hacky. I like your solution better. =)

+    }
   }
 
   # Generate code for variants.