tools/gn: Pass clang-modernize -use-nullptr over it.

tools/gn/functions.cc

Index: tools/gn/functions.cc
diff --git a/tools/gn/functions.cc b/tools/gn/functions.cc
index 84d5ea4312b4fab42ec7c037961a80e24b4d87f7..1cfa6fec7f0735ec5bfaebe6f218f43b5a68cbb4 100644
--- a/tools/gn/functions.cc
+++ b/tools/gn/functions.cc
@@ -600,12 +600,12 @@ Value RunPrint(Scope* scope,
 // -----------------------------------------------------------------------------
 
 FunctionInfo::FunctionInfo()
-    : self_evaluating_args_runner(NULL),
-      generic_block_runner(NULL),
-      executed_block_runner(NULL),
-      no_block_runner(NULL),
-      help_short(NULL),
-      help(NULL),
+    : self_evaluating_args_runner(nullptr),
+      generic_block_runner(nullptr),
+      executed_block_runner(nullptr),
+      no_block_runner(nullptr),
+      help_short(nullptr),
+      help(nullptr),
       is_target(false) {
 }
 
@@ -614,9 +614,9 @@ FunctionInfo::FunctionInfo(SelfEvaluatingArgsFunction seaf,
                            const char* in_help,
                            bool in_is_target)
     : self_evaluating_args_runner(seaf),
-      generic_block_runner(NULL),
-      executed_block_runner(NULL),
-      no_block_runner(NULL),
+      generic_block_runner(nullptr),
+      executed_block_runner(nullptr),
+      no_block_runner(nullptr),
       help_short(in_help_short),
       help(in_help),
       is_target(in_is_target) {
@@ -626,10 +626,10 @@ FunctionInfo::FunctionInfo(GenericBlockFunction gbf,
                            const char* in_help_short,
                            const char* in_help,
                            bool in_is_target)
-    : self_evaluating_args_runner(NULL),
+    : self_evaluating_args_runner(nullptr),
       generic_block_runner(gbf),
-      executed_block_runner(NULL),
-      no_block_runner(NULL),
+      executed_block_runner(nullptr),
+      no_block_runner(nullptr),
       help_short(in_help_short),
       help(in_help),
       is_target(in_is_target) {
@@ -639,10 +639,10 @@ FunctionInfo::FunctionInfo(ExecutedBlockFunction ebf,
                            const char* in_help_short,
                            const char* in_help,
                            bool in_is_target)
-    : self_evaluating_args_runner(NULL),
-      generic_block_runner(NULL),
+    : self_evaluating_args_runner(nullptr),
+      generic_block_runner(nullptr),
       executed_block_runner(ebf),
-      no_block_runner(NULL),
+      no_block_runner(nullptr),
       help_short(in_help_short),
       help(in_help),
       is_target(in_is_target) {
@@ -652,9 +652,9 @@ FunctionInfo::FunctionInfo(NoBlockFunction nbf,
                            const char* in_help_short,
                            const char* in_help,
                            bool in_is_target)
-    : self_evaluating_args_runner(NULL),
-      generic_block_runner(NULL),
-      executed_block_runner(NULL),
+    : self_evaluating_args_runner(nullptr),
+      generic_block_runner(nullptr),
+      executed_block_runner(nullptr),
       no_block_runner(nbf),
       help_short(in_help_short),
       help(in_help),