Suppress SparseArray lint warning in Mojo RouterImpl

org.chromium.mojo.bindings.RouterImpl uses a HashMap<Long, MessageReceiver> to store the callbacks for all Mojo method calls.

Lint complains that this causes unnecessary garbage collection thrashing due to boxing/unboxing of the long map keys, and instead recommends to use an android.util.LongSparseArray.

But LongSparseArray is probably not suitable either, since the documentation says it's "not intended to be appropriate for data structures that may contain large numbers of items".

This patch suppresses the warning for now.

BUG=600699

Review URL: https://codereview.chromium.org/1850793002

Cr-Commit-Position: refs/heads/master@{#385201}

mojo/public/java/bindings/src/org/chromium/mojo/bindings/RouterImpl.java

@@ -4,6 +4,8 @@
 
 package org.chromium.mojo.bindings;
 
+import android.annotation.SuppressLint;
+
 import org.chromium.mojo.system.AsyncWaiter;
 import org.chromium.mojo.system.Core;
 import org.chromium.mojo.system.MessagePipeHandle;
@@ -15,6 +17,7 @@
 /**
  * Implementation of {@link Router}.
  */
+@SuppressLint("UseSparseArrays")  // https://crbug.com/600699
 public class RouterImpl implements Router {
 
     /**