Keep Throwable's constructor that takes a String argument.

Bug: 20495321
Change-Id: Iaf041da325e1d31f136f36e8ed85b2d90c578b0e
diff --git a/core/proguard_basic_keeps.flags b/core/proguard_basic_keeps.flags
index 6b3715a..4de5221 100644
--- a/core/proguard_basic_keeps.flags
+++ b/core/proguard_basic_keeps.flags
@@ -40,6 +40,11 @@
     java.lang.Object readResolve();
 }
 
+# Keep Throwable's constructor that takes a String argument.
+-keepclassmembers class * extends java.lang.Throwable {
+  <init>(java.lang.String);
+}
+
 # Please specify classes to be kept explicitly in your package's configuration.
 # -keep class * extends android.app.Activity
 # -keep class * extends android.view.View