Add proguard_verbose GN arg

build/config/android/config.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.
 
 # This file contains common system config stuff for the Android build.
 
 if (is_android) {
   assert(rebase_path("//", root_build_dir) == "../../",
          "Android output directory must be nested 2 levels within src/ (" +
              "e.g.: out-gn/Debug). http://crbug.com/412935")
@@ skipping 59 matching lines @@
     # chrome (e.g. where to find archived symbols).
     android_chrome_build_id = "\"\""
 
     # Set to true to run findbugs on JAR targets.
     run_findbugs = false
 
     # Set to true to enable verbose findbugs logging. This does nothing if
     # run_findbugs is false.
     findbugs_verbose = false
 
+    # Enables verbose proguard output (summaries and unfiltered output).
+    proguard_verbose = false
+
     # Set to true to enable the Errorprone compiler
     use_errorprone_java_compiler = false
 
     # Enables EMMA Java code coverage. Instruments classes during build to
     # produce .ec files during runtime
     emma_coverage = false
 
     # EMMA filter string consisting of a list of inclusion/exclusion patterns
     # separated with whitespace and/or comma. Only has effect if
     # emma_coverage==true
@@ skipping 153 matching lines @@
   } else if (current_cpu == "x64") {
     android_app_abi = "x86_64"
   } else if (current_cpu == "arm64") {
     android_app_abi = "arm64-v8a"
   } else if (current_cpu == "mips64el") {
     android_app_abi = "mips64"
   } else {
     assert(false, "Unknown Android ABI: " + current_cpu)
   }
 }