Android: Remove -keep for GeneratedMessageLite

No longer needed after recent R8 roll

Change-Id: I1821bf2335f4da02db5f614361755fef24e9b185
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2170559
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Sam Maier <smaier@chromium.org>
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Sam Maier <smaier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#763541}

base/android/proguard/chromium_apk.flags

@@ -60,8 +60,3 @@
   public int getMinApkVersion();
   public boolean requiresSignIn();
 }
-
-# Protobuf java lite runtime uses reflection
--keepclassmembers class * extends com.google.protobuf.GeneratedMessageLite {
-  <fields>;
-}

chrome/android/java/monochrome_public_bundle.proguard_flags.expected

@@ -139,11 +139,6 @@
   public boolean requiresSignIn();
 }
 
-# Protobuf java lite runtime uses reflection
--keepclassmembers class * extends com.google.protobuf.GeneratedMessageLite {
-  <fields>;
-}
-
 ################################################################################
 # ../../base/android/proguard/chromium_code.flags
 ################################################################################