Expose Add/RemoveActionCallback to java

base/android/java/src/org/chromium/base/metrics/RecordUserAction.java

Index: base/android/java/src/org/chromium/base/metrics/RecordUserAction.java
diff --git a/base/android/java/src/org/chromium/base/metrics/RecordUserAction.java b/base/android/java/src/org/chromium/base/metrics/RecordUserAction.java
index 5334746d918caa1076f91318231516809f3322cf..0d2ba548d2ff48fe9eee7a44606d00bfeff25367 100644
--- a/base/android/java/src/org/chromium/base/metrics/RecordUserAction.java
+++ b/base/android/java/src/org/chromium/base/metrics/RecordUserAction.java
@@ -6,6 +6,7 @@ package org.chromium.base.metrics;
 
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 
 /**
@@ -49,5 +50,36 @@ public class RecordUserAction {
         });
     }
 
+    /**
+     * Interface to a class that receives a callback for each UserAction that is recorded.
+     */
+    public interface UserActionCallback {
+        @CalledByNative("UserActionCallback")
+        void onActionRecorded(String action);
+    }
+
+    private static long sNativeActionCallback;
+
+    /**
+     * Register a callback that is executed for each recorded UserAction.
+     * Only one callback can be registered at a time.
+     * The callback has to be unregistered using removeActionCallbackForTesting().
+     */
+    public static void setActionCallbackForTesting(UserActionCallback callback) {
+        assert sNativeActionCallback == 0;
+        sNativeActionCallback = nativeAddActionCallbackForTesting(callback);
+    }
+
+    /**
+     * Unregister the UserActionCallback.
+     */
+    public static void removeActionCallbackForTesting() {
+        assert sNativeActionCallback != 0;
+        nativeRemoveActionCallbackForTesting(sNativeActionCallback);
+        sNativeActionCallback = 0;
+    }
+
     private static native void nativeRecordUserAction(String action);
+    private static native long nativeAddActionCallbackForTesting(UserActionCallback callback);
+    private static native void nativeRemoveActionCallbackForTesting(long callbackId);
 }