Enable R8 for settings

Keep constructor which is only used directly from test.

Update Proguard configuration to include information on checked
exceptions for Mockity to mock thorwn exception.

Bug: 74756073
Test: atest
com.android.settings.deviceinfo.storage.StorageAsyncLoaderTest#testRemovedPackageDoesNotCrash
Utf8ByteLengthFilterTest
Change-Id: Iae87e6647b28ee69d38bd8891df46239779c459c

Android.mk

@@ -11,9 +11,6 @@ include $(BUILD_STATIC_JAVA_LIBRARY)
 # Build the Settings APK
 include $(CLEAR_VARS)
 
-# See b/74756073.
-LOCAL_USE_R8 := false
-
 LOCAL_PACKAGE_NAME := Settings
 LOCAL_PRIVATE_PLATFORM_APIS := true
 LOCAL_CERTIFICATE := platform

proguard.flags

@@ -1,6 +1,10 @@
 # This is a configuration file for ProGuard.
 # http://proguard.sourceforge.net/index.html#manual/usage.html
 
+# Some tests use thenThrow from Mockito which require information on
+# checked exceptions.
+-keepattributes Exceptions
+
 # Keep all Fragments in this package, which are used by reflection.
 -keep public class com.android.settings.** extends android.app.Fragment
 

src/com/android/settings/bluetooth/Utf8ByteLengthFilter.java

@@ -16,6 +16,7 @@
 
 package com.android.settings.bluetooth;
 
+import android.support.annotation.Keep;
 import android.text.InputFilter;
 import android.text.Spanned;
 
@@ -40,6 +41,7 @@ import android.text.Spanned;
 public class Utf8ByteLengthFilter implements InputFilter {
     private final int mMaxBytes;
 
+    @Keep
     Utf8ByteLengthFilter(int maxBytes) {
         mMaxBytes = maxBytes;
     }