extensions: Replace base::MakeUnique with std::make_unique

Should use std::make_unique directly instead of using base::MakeUnique
since August[1]. So, this change removes usages of base::MakeUnique in
//chrome/browser/extensions.

This change removes `#include "base/memory/ptr_util.h"` if it's no more
used in files. (Might not remove if base::WrapUnique is used)

This change also adds `#include <memory>` header except the following
two cases:
  - Not add the header if the file contains the <memory> header
  - Not add the header if the related header contains <memory> header
    (The style guide[2] says that foo.cc can rely on foo.h's includes)

Confirmed no additional lint errors(by `git cl lint`) after this change.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/616016
[2] https://google.github.io/styleguide/cppguide.html#Names_and_Order_of_Includes

Bug: 755727
Change-Id: Iad81c59fef2a7b92eb6d27fb891bc8c19643d32d
Reviewed-on: https://chromium-review.googlesource.com/867171
Reviewed-by: Devlin <[email protected]>
Commit-Queue: Jinho Bang <[email protected]>
Cr-Commit-Position: refs/heads/master@{#529852}
diff --git a/chrome/browser/extensions/extension_system_impl.cc b/chrome/browser/extensions/extension_system_impl.cc
index 867bc44b..73e5ad4b 100644
--- a/chrome/browser/extensions/extension_system_impl.cc
+++ b/chrome/browser/extensions/extension_system_impl.cc
@@ -5,6 +5,7 @@
 #include "chrome/browser/extensions/extension_system_impl.h"
 
 #include <algorithm>
+#include <memory>
 
 #include "base/base_switches.h"
 #include "base/bind.h"
@@ -196,7 +197,7 @@
   LoadErrorReporter::Init(allow_noisy_errors);
 
   content_verifier_ = new ContentVerifier(
-      profile_, base::MakeUnique<ChromeContentVerifierDelegate>(profile_));
+      profile_, std::make_unique<ChromeContentVerifierDelegate>(profile_));
 
   service_worker_manager_.reset(new ServiceWorkerManager(profile_));