[Contacts] Add null check for display name.

Make sure the displayName is not null, which might cause crashes.

Change-Id: Id98c778bba1354dd3e1a1def36f12082b49e5a07
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1916969
Auto-Submit: Rayan Kanso <rayankans@chromium.org>
Reviewed-by: Finnur Thorarinsson <finnur@chromium.org>
Commit-Queue: Rayan Kanso <rayankans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#715379}

chrome/android/java/src/org/chromium/chrome/browser/contacts_picker/ContactDetails.java

@@ -71,7 +71,7 @@ public class ContactDetails implements Comparable<ContactDetails> {
      */
     public ContactDetails(String id, String displayName, List<String> emails,
             List<String> phoneNumbers, List<PaymentAddress> addresses) {
-        mDisplayName = displayName;
+        mDisplayName = displayName != null ? displayName : "";
         mEmails = emails != null ? emails : new ArrayList<String>();
         mPhoneNumbers = phoneNumbers != null ? phoneNumbers : new ArrayList<String>();
         mAddresses = addresses != null ? addresses : new ArrayList<PaymentAddress>();