[GURL] Remove NavigationEntry.getUrlString

Internal repo migrated to new function.
BUG=783819

Change-Id: I00a18ede62983068e2e55698015f156a0c3de216
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2593871Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Commit-Queue: Yaron Friedman <yfriedman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837418}

content/public/android/java/src/org/chromium/content_public/browser/NavigationEntry.java

@@ -58,12 +58,6 @@ public class NavigationEntry {
         return mUrl;
     }
 
-    // NOTE(yfriedman): Use |getUrl| instead. Added to faciliate moving internal repo.
-    @Deprecated
-    public String getUrlString() {
-        return mUrl.getSpec();
-    }
-
     /**
      * @return The virtual URL, when nonempty, will override the actual URL of
      *         the page when we display it to the user. This allows us to have