Clean up NavigationControllerImpl::GetEntryAtOffset.

BUG=none
TEST=none

Review URL: https://codereview.chromium.org/1215893003

Cr-Commit-Position: refs/heads/master@{#336572}
diff --git a/content/browser/frame_host/navigation_controller_impl.cc b/content/browser/frame_host/navigation_controller_impl.cc
index 9824f56..850bdf5 100644
--- a/content/browser/frame_host/navigation_controller_impl.cc
+++ b/content/browser/frame_host/navigation_controller_impl.cc
@@ -527,11 +527,7 @@
 
 NavigationEntryImpl* NavigationControllerImpl::GetEntryAtOffset(
     int offset) const {
-  int index = GetIndexForOffset(offset);
-  if (index < 0 || index >= GetEntryCount())
-    return nullptr;
-
-  return entries_[index];
+  return GetEntryAtIndex(GetIndexForOffset(offset));
 }
 
 int NavigationControllerImpl::GetIndexForOffset(int offset) const {