Expose ability to download network service impl in SDK.

shell/BUILD.gn

Index: shell/BUILD.gn
diff --git a/shell/BUILD.gn b/shell/BUILD.gn
index 3f4838a69c0d969768b0be77038b08bb4ece83f6..58b9c0ec65334f2965d5487d9ed1798a42e02b61 100644
--- a/shell/BUILD.gn
+++ b/shell/BUILD.gn
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/ui.gni")
+import("//build/module_args/mojo.gni")
 import("//mojo/public/mojo.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
@@ -306,6 +307,11 @@ if (is_android) {
       "$root_out_dir/network_service.mojo",
       "$root_out_dir/obj/shell/bootstrap_java.dex.jar",
     ]
+    if (use_prebuilt_network_service) {

[ppi, 2015/02/10 16:49:50]

Is this needed? I'd think that putting "$root_out_dir/network_service.mojo" in
sources would add the dependency. Or is it better to declare it explicitly?

[jamesr, 2015/02/10 22:45:21]

This shouldn't be conditional other than as a transition state.  Building the
shell implies being in the mojo which implies that the network service always
must be prebuilt.  I also agree that this target should just declare a
dependency on $r_o_t/n_s.mojo and let the build system figure out how that file
gets there

[blundell, 2015/02/11 21:06:17]

Done.

+      deps = [
+        "//mojo/public/tools:copy_network_service",
+      ]
+    }
   }
 
   copy("copy_mojo_shell") {