[GN] Add support for generated proguard configs in android_apk

build/config/android/rules.gni

 # Copyright 2014 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.
 
 # Do not add any imports to non-//build directories here.
 # Some projects (e.g. V8) do not have non-build directories DEPS'ed in.
 import("//build/config/android/config.gni")
 import("//build/config/android/internal_rules.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/dcheck_always_on.gni")
@@ skipping 1816 matching lines @@
       _proguard_configs = [ _generated_proguard_config ]
       if (defined(invoker.proguard_configs)) {
         _proguard_configs += invoker.proguard_configs
       }
       assert(_proguard_configs != [])  # Mark as used.
       _proguard_target = "${_template_name}__proguard"
       proguard(_proguard_target) {
         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",
         ]
         inputs = [
                    _build_config,
                    _jar_path,
                  ] + _proguard_configs
 
         output_jar_path = _proguard_output_jar_path
@@ skipping 911 matching lines @@
         # because in practice they seem to contain classes required to be in the
         # classpath.
         deps += _subjar_targets
       }
       if (defined(_res_target_name)) {
         deps += [ ":$_res_target_name" ]
       }
     }
   }
 }