Update to newer Android Lint and suppress new Lint errors

content/public/android/java/src/org/chromium/content/browser/BackgroundSyncNetworkObserver.java

Index: content/public/android/java/src/org/chromium/content/browser/BackgroundSyncNetworkObserver.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/BackgroundSyncNetworkObserver.java b/content/public/android/java/src/org/chromium/content/browser/BackgroundSyncNetworkObserver.java
index fc1bb9a3f9842e33fbed7bb9644f712f089e4487..de51479dce896c8c897fef5fe8e3cacd5ffc3cf7 100644
--- a/content/public/android/java/src/org/chromium/content/browser/BackgroundSyncNetworkObserver.java
+++ b/content/public/android/java/src/org/chromium/content/browser/BackgroundSyncNetworkObserver.java
@@ -5,6 +5,7 @@
 package org.chromium.content.browser;
 
 import android.Manifest;
+import android.annotation.SuppressLint;
 import android.content.pm.PackageManager;
 import android.os.Process;
 
@@ -40,6 +41,8 @@ class BackgroundSyncNetworkObserver implements NetworkChangeNotifierAutoDetect.O
     private NetworkChangeNotifierAutoDetect mNotifier;
 
     // The singleton instance.
+    // TODO(crbug.com/635567): Fix this properly.
+    @SuppressLint("StaticFieldLeak")
     private static BackgroundSyncNetworkObserver sInstance;
 
     // List of native observers. These are each called when the network state changes.