Fix scoped_refptr construction from NULL

This is a precursor to adding a new scoped_refptr(std::nullptr_t)
constructor. The implicit conversion from NULL to scoped_refptr<T>
causes a compilation error with the new constructor. Replace NULL with
nullptr in any files where this is a problem.

This CL was uploaded by git cl split.

[email protected]

Bug: 1018887
Change-Id: Ifd7c2f17a6be0dcc075020d090f62af299d46708
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1885012
Auto-Submit: kylechar <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Commit-Queue: Scott Violet <[email protected]>
Cr-Commit-Position: refs/heads/master@{#710214}
diff --git a/chrome/browser/safe_browsing/ui_manager_unittest.cc b/chrome/browser/safe_browsing/ui_manager_unittest.cc
index d8903e3..ec739ec2 100644
--- a/chrome/browser/safe_browsing/ui_manager_unittest.cc
+++ b/chrome/browser/safe_browsing/ui_manager_unittest.cc
@@ -79,7 +79,7 @@
  public:
   SafeBrowsingUIManagerTest()
       : scoped_testing_local_state_(TestingBrowserProcess::GetGlobal()) {
-    ui_manager_ = new SafeBrowsingUIManager(NULL);
+    ui_manager_ = new SafeBrowsingUIManager(nullptr);
   }
 
   ~SafeBrowsingUIManagerTest() override {}