Add Proguard rules

build.gradle

@@ -67,7 +67,9 @@ android {
             signingConfig signingConfigs.debug
         }
         release {
-            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard.flags'
+            minifyEnabled true
+            shrinkResources true
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
             signingConfig releaseSigning
         }
 

proguard-rules.pro

@@ -0,0 +1,32 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
+
+-keepclasseswithmembernames,includedescriptorclasses class * {
+    native <methods>;
+}
+
+-keepclasseswithmembers class * {
+    native <methods>;
+}
+
+-dontobfuscate
+-optimizations !code/allocation/variable