Adding option for Proguard jar to be switched.

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 71 matching lines @@
     # 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
 
+    # Java debug on Android. Having this on enables multidexing, and turning it
+    # off will enable proguard.
+    is_java_debug = is_debug

[Peter Wen, 2016/06/06 20:28:16]

Can you explain why we want is_java_debug?

Right now most developers have is_debug explicitly set to true or false, this
line seems to make the default value of is_java_debug equal to is_debug. If the
user did not explicitly set is_java_debug in gn args, does it follow the
explicitly set value of is_debug? i.e. will this cause strange behaviour when
is_debug is explicitly set to false, and is_java_debug ends up being true?

[smaier, 2016/06/06 21:04:58]

The current behaviour would continue as normal for those that did not set
is_java_debug. I am creating this to allow us to do non-debug Java features (eg.
Proguard) while still building a typical debug build.

[Peter Wen, 2016/06/06 21:45:23]

I see. I feel that setting is_debug to false in gn will not result in
is_java_debug being set to false. That's not a bad thing, just we'll need to
communicate to the team that when they want a release proguarded build, they
need to explicitly set this new gn arg. If that's the case, something like
"run_proguard" may be a better name.

Adding pkotwicz to confirm my understanding.

[smaier, 2016/06/07 18:20:45]

This is a pretty common pattern, for example line 116 is "enable_incremental_dx
= is_debug". I did try this locally and setting is_debug in gn args sets
is_java_debug.

+
     # 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 161 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}"
   }
 }