Fixing WebView ProGuard config for annotations

android_webview/apk/java/proguard.flags

Index: android_webview/apk/java/proguard.flags
diff --git a/android_webview/apk/java/proguard.flags b/android_webview/apk/java/proguard.flags
index 3b3f2c6332c785919eb2762e8f1b48b528df1f42..3589ce9223dbc7bce601fd148fd6dafed6a9766c 100644
--- a/android_webview/apk/java/proguard.flags
+++ b/android_webview/apk/java/proguard.flags
@@ -8,10 +8,14 @@
 
 # Keep all runtime visible annotations.
 -keepattributes RuntimeVisibleAnnotations
-
-# Disable optimization as this causes proguard to remove seemingly random stuff,
-# including things explicitly kept in this configuration.
--dontoptimize
+# Keeping annotations - if we remove these keeps, ProGuard will eliminate the
+# annotations themselves, which will prevent them from affecting ProGuard's
+# optimization run.
+-keep @interface **.AccessedByNative
+-keep @interface **.CalledByNative
+-keep @interface **.CalledByNativeUnchecked
+-keep @interface **.RemovableInRelease
+-keep @interface **.UsedByReflection
 
 # Keep the factory and its public members; it's the main entry point used by the
 # framework.
@@ -39,11 +43,19 @@
   native <methods>;
 }
 
-# Keep things explicitly marked as used by reflection
+# Keep classes marked as used by reflection
+-keep @**.UsedByReflection class com.android.webview.chromium.**,org.chromium.**
+
+# Keep members explicitly marked as used by reflection
 -keepclasseswithmembers class com.android.webview.chromium.**,org.chromium.** {
   @**.UsedByReflection *;
 }
 
+# Remove methods annotated with this if their return value is unused
+-assumenosideeffects class ** {
+  @org.chromium.base.annotations.RemovableInRelease <methods>;
+}
+
 # Linker dynamically casts to $TestRunner when running tests. We don't run these
 # tests in WebView.
 -dontnote org.chromium.base.library_loader.Linker$TestRunner