Removed keeps for unused member variables.

chrome/android/java/proguard.flags

 # Keep line number information, useful for stack traces.
 -keepattributes SourceFile,LineNumberTable
 
 # Keep the annotations.
 -keep @interface ***
 
 # Disable obfuscation for the following two packages.
 -keepnames class com.google.android.apps.chrome.**,org.chromium.** {
   *;
 }
 
-# Keep all the primitive and String constants for for the following two packages.
--keepclassmembers class com.google.android.apps.chrome.**,org.chromium.** {
-  !private static final % *;
-  !private static final java.lang.String *;
-}
-
 # Keep code annotated with the following annotations.
 -keep class com.google.android.apps.chrome.**,org.chromium.** {
   @**.AccessedByNative <fields>;
   @**.CalledByNative <methods>;
   @**.CalledByNativeUnchecked <methods>;
   @**.JavascriptInterface <methods>;
   @**.NativeCall <methods>;
   @**.UsedByReflection <methods>;
   @**.VisibleForTesting *;
   native <methods>;
@@ skipping 139 matching lines @@
 # Needed to run ChromeTest.apk
 -keepnames class com.google.android.gms.common.GoogleApiAvailability {
   *;
 }
 
 #-keep public class android.net.http.SslCertificate
 #-keep public class android.webkit.WebVie
 
 #-dontwarn android.webkit.WebView
 -dontwarn android.net.http.SslCertificate