Adding option for Proguard jar to be switched.

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index d49a22d8f1caf35bd9e54ceaaedcd0b1f8e5a983..fdd1b6655423f78719befa9b1c0a4ac071620f04 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -2372,6 +2372,11 @@ if (is_android) {
       "android/java/templates/BuildConfig.template",
     ]
     package_name = "org/chromium/base"
+
+    defines = []
+    if (is_java_debug) {

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

Guarding this on is_debug is more intuitive, as if I set is_debug = false, I
don't think I'd ever expect BuildConfig.IS_DEBUG to be true.

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

This would only be the case if you explicitly set is_java_debug to true, in
which case I think you would expect BuildConfig.IS_DEBUG (a Java constant) to be
true. Perhaps IS_DEBUG should be changed to IS_JAVA_DEBUG for more clarity in
the build files? However, that seems a bit obtuse once you're in a Java file and
having to check for IS_JAVA_DEBUG.

+      defines += [ "DEBUG" ]
+    }
   }
 
   # GYP: //base/base.gyp:base_native_libraries_gen