Replace s/NULL/nullptr/ in field initializers used in constructors.

This change has been generated by a clang tool developed for the
go/miracleptr project.

Bug: 1080832
Change-Id: Ie7f428c8ad300db1df95d873668163d0ac719a22
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2231843
Reviewed-by: Kentaro Hara <[email protected]>
Reviewed-by: Bartek Nowierski <[email protected]>
Commit-Queue: Ɓukasz Anforowicz <[email protected]>
Cr-Commit-Position: refs/heads/master@{#776343}
diff --git a/chrome/browser/extensions/api/debugger/debugger_api.cc b/chrome/browser/extensions/api/debugger/debugger_api.cc
index 253ce75..3aaf286 100644
--- a/chrome/browser/extensions/api/debugger/debugger_api.cc
+++ b/chrome/browser/extensions/api/debugger/debugger_api.cc
@@ -389,9 +389,7 @@
 
 // DebuggerFunction -----------------------------------------------------------
 
-DebuggerFunction::DebuggerFunction()
-    : client_host_(NULL) {
-}
+DebuggerFunction::DebuggerFunction() : client_host_(nullptr) {}
 
 DebuggerFunction::~DebuggerFunction() = default;