[GN] Add support for generated proguard configs in android_apk

build/config/android/rules.gni

Index: build/config/android/rules.gni
diff --git a/build/config/android/rules.gni b/build/config/android/rules.gni
index 2cc550bc3dade4091a87d0af802e73299303dd0f..b889b6ce89c102b94148f9c5df5d999949dac6e1 100644
--- a/build/config/android/rules.gni
+++ b/build/config/android/rules.gni
@@ -1834,9 +1834,10 @@ if (enable_java_templates) {
         forward_variables_from(invoker,
                                [
                                  "alternative_android_sdk_jar",
+                                 "deps",
                                  "proguard_jar_path",
                                ])
-        deps = [
+        deps += [

[kapishnikov, 2016/11/30 18:02:18]

Will add:
      if (defined(deps)) {
        deps += [ ... ]
      } else {
        deps = [ ... ]
      }

[jbudorick, 2016/11/30 18:05:40]

nit: do

  if (!defined(deps)) {
    deps = []
  }

  deps += [ ... ]

           ":$build_config_target",
           ":$java_target",
           ":$process_resources_target",