Android: Proguard rules to allow shrinking for <native>

base/android/proguard/chromium_code.flags

Index: base/android/proguard/chromium_code.flags
diff --git a/base/android/proguard/chromium_code.flags b/base/android/proguard/chromium_code.flags
index a2ad4404f73e592038848a033d0028e2ca24ba25..49336905ab3043b44b3daa9f55a4bacc70d314e3 100644
--- a/base/android/proguard/chromium_code.flags
+++ b/base/android/proguard/chromium_code.flags
@@ -25,6 +25,8 @@
 -keepclasseswithmembers class * {
   @org.chromium.base.annotations.AccessedByNative <fields>;
 }
+# -includedescriptorclasses tells it to also keep return types and parameter
+# types.
 -keepclasseswithmembers,includedescriptorclasses class * {
   @org.chromium.base.annotations.CalledByNative <methods>;
 }
@@ -37,7 +39,9 @@
 -keepclasseswithmembers class * {
   @org.chromium.base.annotations.UsedByReflection <fields>;
 }
--keepclasseswithmembers,includedescriptorclasses class * {
+# -keepclasseswithmembernames rather than -keepclasseswithmembers to allow
+# shrinking if it contains native methods but no @CalledByNative.
+-keepclasseswithmembernames,includedescriptorclasses class * {
   native <methods>;
 }