Make sure the Async test cases availabel today generate correct ClientID.

chrome/android/java/src/org/chromium/chrome/browser/tab/TabContextMenuItemDelegate.java

Index: chrome/android/java/src/org/chromium/chrome/browser/tab/TabContextMenuItemDelegate.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tab/TabContextMenuItemDelegate.java b/chrome/android/java/src/org/chromium/chrome/browser/tab/TabContextMenuItemDelegate.java
index c65885e46b5e83f9b0ad66dc81dd60ec13b3a17f..c02f0c4624a83bbab8f949026ebd4cf862b6d4a0 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tab/TabContextMenuItemDelegate.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tab/TabContextMenuItemDelegate.java
@@ -26,7 +26,7 @@ import org.chromium.ui.base.PageTransition;
 
 import java.net.URI;
 import java.util.Locale;
-import java.util.Random;
+import java.util.UUID;
 
 /**
  * A default {@link ContextMenuItemDelegate} that supports the context menu functionality in Tab.
@@ -170,9 +170,9 @@ public class TabContextMenuItemDelegate implements ContextMenuItemDelegate {
     @Override
     public void onSavePageLater(String linkUrl) {
         OfflinePageBridge bridge = OfflinePageBridge.getForProfile(mTab.getProfile());
-        Random random = new Random();
-        long offline_id = random.nextLong();
-        ClientId clientId = new ClientId("async_loading", Long.toString(offline_id));
+        // Download UI needs "async_loading" namespace and a type 4 (random) GUID.

[chili, 2016/07/27 18:40:47]

nit: can we leave out the 'type 4' in the comments?  Nothing in the code refers
to this as a type 4 GUID, which makes this confusing.  Can also do 'a random
(type 4) GUID' as well

[Dmitry Titov, 2016/07/27 19:50:49]

Done.

+        String uuid = UUID.randomUUID().toString();
+        ClientId clientId = new ClientId("async_loading", uuid);
         bridge.savePageLater(linkUrl, clientId);
     }