Revert "Remove abandoned implementation."

Revert submission 3242160-remove-messaging-package

Reason for revert: Droidmonitor created revert due to b/364617310, b/364626927, b/364617560

Reverted changes: /q/submissionid:3241481-remove-messaging-package

This reverts commit 93b5e63726.

Change-Id: I182cbf1758988d9a4950d39354266a5fb3aaabce

proguard.flags

@@ -0,0 +1,64 @@
+#  Copyright (C) 2015 The Android Open Source Project
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+# Keep enough data for stack traces
+-renamesourcefileattribute SourceFile
+-keepattributes SourceFile,LineNumberTable,*Annotation*
+
+# Keep classes and methods that have the guava @VisibleForTesting annotation
+-keep @com.google.common.annotations.VisibleForTesting class *
+-keepclassmembers class * {
+  @com.google.common.annotations.VisibleForTesting *;
+}
+-keep class com.android.messaging.* { *; }
+-keep class com.android.messaging.*.* { *; }
+-keep class com.android.messaging.*.*.* { *; }
+
+# Keep methods that have the @VisibleForAnimation annotation
+-keep @interface com.android.messaging.annotation.VisibleForAnimation
+-keepclassmembers class * {
+  @com.android.messaging.annotation.VisibleForAnimation *;
+}
+
+-keep public class * extends android.app.Activity
+-keep public class * extends android.app.Application
+-keep public class * extends android.app.Service
+-keep public class * extends android.content.BroadcastReceiver
+-keep public class * extends android.content.ContentProvider
+-keep public class * extends android.app.backup.BackupAgentHelper
+-keep public class * extends android.preference.Preference
+-keep public class * extends androidx.fragment.app.Fragment
+-keep public class com.android.vcard.* { *; }
+
+-keep class androidx.collection.* { *; }
+-keep class androidx.core.* { *; }
+-keep class androidx.core.*.* { *; }
+-keep class androidx.appcompat.* { *; }
+-keep class androidx.appcompat.*.* { *; }
+-keep class androidx.recyclerview.widget.* { *; }
+-keep class androidx.viewpager.widget.* { *; }
+
+# Keep rastermill classes that need to be accessed from native code (JNI)
+-keep class android.support.rastermill.** { *; }
+
+# Preserve the name of the getCaller method so it can find itself in the stack trace it generates
+-keepclassmembers public class com.android.messaging.util.DebugUtils {
+  public static java.lang.StackTraceElement getCaller(...);
+}
+
+# Keep the static fields of referenced inner classes of auto-generated R classes, in case we
+# access those fields by reflection (e.g. EmojiMarkup)
+-keepclassmembers class **.R$* {
+    public static <fields>;
+}