Run clang-modernize -use-nullptr over src/extensions/.

extensions/common/extension_set.cc

Index: extensions/common/extension_set.cc
diff --git a/extensions/common/extension_set.cc b/extensions/common/extension_set.cc
index c4c15d4e1f2bc3b8f291f590f7be0b109a21583e..5a1bd1812e79fa5890ffde7faa40b0bfee74ba91 100644
--- a/extensions/common/extension_set.cc
+++ b/extensions/common/extension_set.cc
@@ -91,7 +91,7 @@ const Extension* ExtensionSet::GetExtensionOrAppByURL(const GURL& url) const {
 
 const Extension* ExtensionSet::GetAppByURL(const GURL& url) const {
   const Extension* extension = GetExtensionOrAppByURL(url);
-  return (extension && extension->is_app()) ? extension : NULL;
+  return (extension && extension->is_app()) ? extension : nullptr;
 }
 
 const Extension* ExtensionSet::GetHostedAppByURL(const GURL& url) const {
@@ -101,7 +101,7 @@ const Extension* ExtensionSet::GetHostedAppByURL(const GURL& url) const {
       return iter->second.get();
   }
 
-  return NULL;
+  return nullptr;
 }
 
 const Extension* ExtensionSet::GetHostedAppByOverlappingWebExtent(
@@ -112,7 +112,7 @@ const Extension* ExtensionSet::GetHostedAppByOverlappingWebExtent(
       return iter->second.get();
   }
 
-  return NULL;
+  return nullptr;
 }
 
 bool ExtensionSet::InSameExtent(const GURL& old_url,
@@ -126,7 +126,7 @@ const Extension* ExtensionSet::GetByID(const std::string& id) const {
   if (i != extensions_.end())
     return i->second.get();
   else
-    return NULL;
+    return nullptr;
 }
 
 ExtensionIdSet ExtensionSet::GetIDs() const {