Don't allow proguard to rename Parcelables at all.

base/android/base_proguard_config.flags

Index: base/android/base_proguard_config.flags
diff --git a/base/android/base_proguard_config.flags b/base/android/base_proguard_config.flags
index 00cf22b52682a0a6d0dadd0b02714e07d3e4f388..f8b733d346ca196506d994dc9450796f5650b7b6 100644
--- a/base/android/base_proguard_config.flags
+++ b/base/android/base_proguard_config.flags
@@ -38,6 +38,8 @@
 }
 
 # Keep all Parcelables as they might be marshalled outside Chrome.
+-keepnames class * implements android.os.Parcelable
+
 -keepclassmembers class * implements android.os.Parcelable {
   public static *** CREATOR;
 }