Java: Introduce ResultAnd<> and use it.

mojo/android/javatests/src/org/chromium/mojo/HandleMock.java

Index: mojo/android/javatests/src/org/chromium/mojo/HandleMock.java
diff --git a/mojo/android/javatests/src/org/chromium/mojo/HandleMock.java b/mojo/android/javatests/src/org/chromium/mojo/HandleMock.java
index 427fbec0360ce3ac557ca0500b61bb4d91aa9283..6783c0903d728261056ff2e0321c2e2621cc2385 100644
--- a/mojo/android/javatests/src/org/chromium/mojo/HandleMock.java
+++ b/mojo/android/javatests/src/org/chromium/mojo/HandleMock.java
@@ -12,6 +12,7 @@ import org.chromium.mojo.system.DataPipe.ProducerHandle;
 import org.chromium.mojo.system.Handle;
 import org.chromium.mojo.system.MessagePipeHandle;
 import org.chromium.mojo.system.MojoResult;
+import org.chromium.mojo.system.ResultAnd;
 import org.chromium.mojo.system.SharedBufferHandle;
 import org.chromium.mojo.system.UntypedHandle;
 import org.chromium.mojo.system.impl.CoreImpl;
@@ -97,10 +98,9 @@ public class HandleMock implements UntypedHandle, MessagePipeHandle,
      * @see ConsumerHandle#readData(java.nio.ByteBuffer, DataPipe.ReadFlags)
      */
     @Override
-    public int readData(ByteBuffer elements,
-            DataPipe.ReadFlags flags) {
+    public ResultAnd<Integer> readData(ByteBuffer elements, DataPipe.ReadFlags flags) {
         // Do nothing.
-        return 0;
+        return new ResultAnd<Integer>(MojoResult.OK, 0);
     }
 
     /**
@@ -125,10 +125,9 @@ public class HandleMock implements UntypedHandle, MessagePipeHandle,
      * @see ProducerHandle#writeData(java.nio.ByteBuffer, DataPipe.WriteFlags)
      */
     @Override
-    public int writeData(ByteBuffer elements,
-            DataPipe.WriteFlags flags) {
+    public ResultAnd<Integer> writeData(ByteBuffer elements, DataPipe.WriteFlags flags) {
         // Do nothing.
-        return 0;
+        return new ResultAnd<Integer>(MojoResult.OK, 0);
     }
 
     /**
@@ -163,10 +162,10 @@ public class HandleMock implements UntypedHandle, MessagePipeHandle,
      * @see MessagePipeHandle#readMessage(java.nio.ByteBuffer, int, MessagePipeHandle.ReadFlags)
      */
     @Override
-    public ReadMessageResult readMessage(ByteBuffer bytes, int maxNumberOfHandles,
-            ReadFlags flags) {
+    public ResultAnd<ReadMessageResult> readMessage(
+            ByteBuffer bytes, int maxNumberOfHandles, ReadFlags flags) {
         // Do nothing.
-        return new ReadMessageResult();
+        return new ResultAnd<ReadMessageResult>(MojoResult.OK, new ReadMessageResult());
     }
 
     /**