Style Change: NULL->nullptr
DOCS_PREVIEW= https://skia.org/?cl=1316233002

Review URL: https://codereview.chromium.org/1316233002
diff --git a/tools/flags/SkCommandLineFlags.cpp b/tools/flags/SkCommandLineFlags.cpp
index 2ea45c2..fe3dfd1 100644
--- a/tools/flags/SkCommandLineFlags.cpp
+++ b/tools/flags/SkCommandLineFlags.cpp
@@ -29,7 +29,7 @@
 void SkFlagInfo::SetDefaultStrings(SkCommandLineFlags::StringArray* pStrings,
                                    const char* defaultValue) {
     pStrings->reset();
-    if (NULL == defaultValue) {
+    if (nullptr == defaultValue) {
         return;
     }
     // If default is "", leave the array empty.
@@ -268,7 +268,7 @@
         if (!helpPrinted) {
             bool flagMatched = false;
             SkFlagInfo* flag = gHead;
-            while (flag != NULL) {
+            while (flag != nullptr) {
                 if (flag->match(argv[i])) {
                     flagMatched = true;
                     switch (flag->getFlagType()) {
@@ -287,7 +287,7 @@
                             flag->resetStrings();
                             // Add all arguments until another flag is reached.
                             while (i+1 < argc) {
-                                char* end = NULL;
+                                char* end = nullptr;
                                 // Negative numbers aren't flags.
                                 ignore_result(strtod(argv[i+1], &end));
                                 if (end == argv[i+1] && SkStrStartsWith(argv[i+1], '-')) {
@@ -331,8 +331,8 @@
     // Since all of the flags have been set, release the memory used by each
     // flag. FLAGS_x can still be used after this.
     SkFlagInfo* flag = gHead;
-    gHead = NULL;
-    while (flag != NULL) {
+    gHead = nullptr;
+    while (flag != nullptr) {
         SkFlagInfo* next = flag->next();
         delete flag;
         flag = next;