Creating new gn arg: enable_all_proguard_optimizations.

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 99 matching lines @@
 
     # EMMA filter string consisting of a list of inclusion/exclusion patterns
     # separated with whitespace and/or comma. Only has effect if
     # emma_coverage==true
     emma_filter = ""
 
     # Disables process isolation when building _incremental targets.
     # Required for Android M+ due to SELinux policies (stronger sandboxing).
     disable_incremental_isolated_processes = false
 
+    # Enables all ProGuard optimizations. These optimizations must not be
+    # enabled for instrumentation tests, as they break the tests.

[agrieve, 2016/07/08 14:26:20]

nit: change ", as they break the tests" -> "since they cause code required by
the tests to be removed"

[smaier, 2016/07/08 14:50:07]

Done.

+    enable_all_proguard_optimizations = is_official_build
+
     # Speed up incremental compiles by compiling only changed files.
     enable_incremental_javac = false
 
     # Speed up dexing using dx --incremental.
     enable_incremental_dx = is_java_debug
 
     # Neither of these should ever be used for release builds since they are
     # somewhat experimental and dx --incremental is known to not produce
     # byte-for-byte identical output.
     assert(!(enable_incremental_dx && !is_java_debug))
@@ skipping 145 matching lines @@
   } else if (current_cpu == "mips64el") {
     android_app_abi = "mips64"
   } else {
     assert(false, "Unknown Android ABI: " + current_cpu)
   }
 
   if (android_libcpp_lib_dir == "") {
     android_libcpp_lib_dir = "${android_libcpp_root}/libs/${android_app_abi}"
   }
 }