Split cronet.jar into cronet.jar and cronet_api.jar, preserve full libcronet.so

components/cronet/android/proguard.cfg

Index: components/cronet/android/proguard.cfg
diff --git a/components/cronet/android/proguard.cfg b/components/cronet/android/proguard.cfg
index 7d1fe1a435ee5da1e9a0f25b0bac0ac907c5253a..938960ae9922af82f8e611362b9289935f46d7fe 100644
--- a/components/cronet/android/proguard.cfg
+++ b/components/cronet/android/proguard.cfg
@@ -7,8 +7,21 @@
 -keepclasseswithmembers class org.chromium.** {
     @org.chromium.base.*Native* <methods>;
 }
--keep @org.chromium.base.JNINamespace class org.chromium.** {
+
+# TODO(mef) remove unnecessary classes from base, so we don't have to preserve
+# their methods
+-keepclasseswithmembers class org.chromium.** {
     native <methods>;
 }
+
 -dontnote org.chromium.net.AndroidKeyStore
 
+# Needed so that multiple optimization passes will detect annotations
+-keepattributes *Annotation*
+
+# Keep methods used by reflection and native code
+-keep class org.chromium.net.UsedBy*
+-keep @org.chromium.net.UsedBy* class *
+-keepclassmembers class * {
+    @org.chromium.net.UsedBy* *;
+}