Adding option for Proguard jar to be switched.

build/config/android/config.gni

Index: build/config/android/config.gni
diff --git a/build/config/android/config.gni b/build/config/android/config.gni
index 98b4aa614bf992a7ab89aff634a97dd6b9427baf..bcda6ecabe8e4fcfb4b05e9215d09584d2e0aa55 100644
--- a/build/config/android/config.gni
+++ b/build/config/android/config.gni
@@ -89,6 +89,10 @@ if (is_android) {
     # 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