Enable Java 8 by default

base/android/java/src/org/chromium/base/Callback.java

Index: base/android/java/src/org/chromium/base/Callback.java
diff --git a/base/android/java/src/org/chromium/base/Callback.java b/base/android/java/src/org/chromium/base/Callback.java
index ee5857d639e726b68afcac5b41fd519d067ea7b1..75aa7222ad645d5e959b97da9c922fb5fc3501dc 100644
--- a/base/android/java/src/org/chromium/base/Callback.java
+++ b/base/android/java/src/org/chromium/base/Callback.java
@@ -11,27 +11,27 @@ import org.chromium.base.annotations.CalledByNative;
  *
  * @param <T> The type of the computation's result.
  */
-public abstract class Callback<T> {
+public interface Callback<T> {
     /**
      * Invoked with the result of a computation.
      */
-    public abstract void onResult(T result);
+    void onResult(T result);
 
     @SuppressWarnings("unchecked")
     @CalledByNative
-    private void onResultFromNative(Object result) {
-        onResult((T) result);
+    static void onResultFromNative(Callback callback, Object result) {
+        callback.onResult(result);
     }
 
     @SuppressWarnings("unchecked")
     @CalledByNative
-    private void onResultFromNative(boolean result) {
-        onResult((T) Boolean.valueOf(result));
+    static void onResultFromNative(Callback callback, boolean result) {
+        callback.onResult(Boolean.valueOf(result));
     }
 
     @SuppressWarnings("unchecked")
     @CalledByNative
-    private void onResultFromNative(int result) {
-        onResult((T) Integer.valueOf(result));
+    static void onResultFromNative(Callback callback, int result) {
+        callback.onResult(Integer.valueOf(result));
     }
 }