[WebLayer] Make GoogleAccountsParams constructor public

This is necessary for mocking calls to `onGoogleAccountsRequest` in
tests.

Change-Id: Ia7a99ce052071b8728f30710491194d8da6a8b96
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2396158
Auto-Submit: Tim Sergeant <tsergeant@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Clark DuVall <cduvall@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804971}

weblayer/public/java/org/chromium/weblayer/GoogleAccountsParams.java

@@ -34,8 +34,8 @@ public class GoogleAccountsParams {
      */
     public final boolean isSameTab;
 
-    GoogleAccountsParams(@GoogleAccountServiceType int serviceType, String email, Uri continueUri,
-            boolean isSameTab) {
+    public GoogleAccountsParams(@GoogleAccountServiceType int serviceType, String email,
+            Uri continueUri, boolean isSameTab) {
         this.serviceType = serviceType;
         this.email = email;
         this.continueUri = continueUri;