Add proguard_verbose GN arg

build/config/android/internal_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.
 
 import("//build/config/android/config.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/zip.gni")
 import("//third_party/ijar/ijar.gni")
 
 assert(is_android)
@@ skipping 103 matching lines @@
     args = [
       "--depfile",
       rebase_path(depfile, root_build_dir),
       "--proguard-path",
       rebase_path(_proguard_jar_path, root_build_dir),
       "--output-path",
       rebase_path(_output_jar_path, root_build_dir),
       "--classpath",
       _rebased_android_sdk_jar,
     ]
+    if (proguard_verbose) {
+      args += [ "--verbose" ]
+    }
     if (defined(invoker.args)) {
       args += invoker.args
     }
   }
 }
 
 template("findbugs") {
   jar_path = invoker.jar_path
 
   build_config = invoker.build_config
@@ skipping 1929 matching lines @@
     ]
     args = [
       "--depfile",
       rebase_path(depfile, root_build_dir),
       "--script-output-path",
       rebase_path(generated_script, root_build_dir),
     ]
     args += test_runner_args
   }
 }