Added UnguessableToken.java .

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

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.base;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import org.chromium.base.annotations.CalledByNative;
+
+/**
+ * This class mirrors unguessable_token.h .  Since tokens are passed by value,
+ * we don't bother to maintain a native token.  This implements Parcelable so
+ * that it may be sent via binder.
+ *
+ * To get one of these from native, one must start with a
+ * base::UnguessableToken, then create a java object from it.  See

[nyquist, 2016/11/08 19:04:42]

Nit: Java here and in the TODO

[liberato (no reviews please), 2016/11/09 18:18:33]

Done.

+ * jni_unguessable_token.h for information.
+ */
+public class UnguessableToken implements Parcelable {
+    private long mHigh;

[nyquist, 2016/11/08 19:04:42]

final for these two fields.

[liberato (no reviews please), 2016/11/09 18:18:33]

Done.

+    private long mLow;
+
+    private UnguessableToken(long high, long low) {
+        mHigh = high;
+        mLow = low;
+    }
+
+    @CalledByNative
+    private static UnguessableToken create(long high, long low) {
+        return new UnguessableToken(high, low);
+    }
+
+    @CalledByNative
+    private long getHighForSerialization() {
+        return mHigh;
+    }
+
+    @CalledByNative
+    private long getLowForSerialization() {
+        return mLow;
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(Parcel dest, int flags) {
+        dest.writeLong(mHigh);
+        dest.writeLong(mLow);
+    }
+
+    public static final Parcelable.Creator<UnguessableToken> CREATOR =
+            new Parcelable.Creator<UnguessableToken>() {
+                @Override
+                public UnguessableToken createFromParcel(Parcel source) {
+                    final long high = source.readLong();

[nyquist, 2016/11/08 19:04:42]

Nit: unnecessary final here and below

[liberato (no reviews please), 2016/11/09 18:18:33]

Done.

+                    final long low = source.readLong();
+                    if (high == 0 || low == 0) {
+                        // Refuse to create an empty UnguessableToken.
+                        return null;
+                    }
+                    return new UnguessableToken(high, low);
+                }
+
+                @Override
+                public UnguessableToken[] newArray(int size) {
+                    return new UnguessableToken[size];
+                }
+            };
+
+    // To avoid unwieldy calls in JNI for tests, parcel and unparcel.
+    // TODO(liberato): It would be nice if we could include this only with a
+    // java driver that's linked only with unit tests, but i don't see a way
+    // to do that.
+    @CalledByNative
+    private UnguessableToken parcelAndUnparcelForTesting() {
+        Parcel parcel = Parcel.obtain();
+        writeToParcel(parcel, 0);
+
+        // Rewind the parcel and un-parcel.
+        parcel.setDataPosition(0);
+        UnguessableToken token = CREATOR.createFromParcel(parcel);
+        parcel.recycle();
+
+        return token;
+    }
+};