Removing protobuf ProGuard keep

chrome/android/java/proguard.flags

 # Disable obfuscation for the following two packages.
 -keepnames,allowoptimization class com.google.android.apps.chrome.**,org.chromium.** {
   *;
 }
 
 # Fragments are loaded using reflection via Fragment.instantiate(Context,String)
 # This can be improved upon - see crbug.com/622023.
 -keep public class com.google.android.apps.chrome** extends android.app.Fragment
 -keep public class org.chromium** extends android.app.Fragment
 
-# Keep protobuf code used via reflection
-# TODO(tonyg): Removing these -keeps results in new notes, but nothing seems to
-# break. This exclusion costs almost 100k of dex size so consider replacing it
-# with a -dontnote after more testing.
--keep class com.google.protobuf.** {
-  *** newBuilder();
-  *** parseFrom(java.io.InputStream);
-}
-
 # Keep the client interfaces for cacheinvalidation as they are used as
 # argument types for some of our code that we're keeping and proguard warns
 # otherwise.
 -keep class com.google.ipc.invalidation.external.client.** {
   *;
 }
 
 # Keep all Parcelables as they might be marshalled outside Chrome.
 -keepnames class * implements android.os.Parcelable {
    public static final ** CREATOR;
@@ skipping 12 matching lines @@
 # Don't warn about those in case this app is linking against an older
 # platform version.  We know about them, and they are safe.
 -dontwarn android.support.**
 
 # Proguard mistakenly optimizes away some null checks on final fields
 # in the support library.
 # See https://sourceforge.net/p/proguard/bugs/531/#fdc9/41e2
 -keepclassmembers,allowshrinking,allowobfuscation class android.support.v7.widget.AppCompatButton {
   !static final <fields>;
 }