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

tools/gn/escape_unittest.cc

Index: tools/gn/escape_unittest.cc
diff --git a/tools/gn/escape_unittest.cc b/tools/gn/escape_unittest.cc
index fd4934861e4b84997bb0390de4cd70e02a3c8abe..f2b2eae19742e1451b17a5126d8710cf85275f1c 100644
--- a/tools/gn/escape_unittest.cc
+++ b/tools/gn/escape_unittest.cc
@@ -8,7 +8,7 @@
 TEST(Escape, Ninja) {
   EscapeOptions opts;
   opts.mode = ESCAPE_NINJA;
-  std::string result = EscapeString("asdf: \"$\\bar", opts, NULL);
+  std::string result = EscapeString("asdf: \"$\\bar", opts, nullptr);
   EXPECT_EQ("asdf$:$ \"$$\\bar", result);
 }
 
@@ -18,7 +18,7 @@ TEST(Escape, WindowsCommand) {
   opts.platform = ESCAPE_PLATFORM_WIN;
 
   // Regular string is passed, even if it has backslashes.
-  EXPECT_EQ("foo\\bar", EscapeString("foo\\bar", opts, NULL));
+  EXPECT_EQ("foo\\bar", EscapeString("foo\\bar", opts, nullptr));
 
   // Spaces means the string is quoted, normal backslahes untouched.
   bool needs_quoting = false;
@@ -33,10 +33,10 @@ TEST(Escape, WindowsCommand) {
   opts.inhibit_quoting = false;
 
   // Backslashes at the end of the string get escaped.
-  EXPECT_EQ("\"foo$ bar\\\\\\\\\"", EscapeString("foo bar\\\\", opts, NULL));
+  EXPECT_EQ("\"foo$ bar\\\\\\\\\"", EscapeString("foo bar\\\\", opts, nullptr));
 
   // Backslashes preceeding quotes are escaped, and the quote is escaped.
-  EXPECT_EQ("\"foo\\\\\\\"$ bar\"", EscapeString("foo\\\" bar", opts, NULL));
+  EXPECT_EQ("\"foo\\\\\\\"$ bar\"", EscapeString("foo\\\" bar", opts, nullptr));
 }
 
 TEST(Escape, PosixCommand) {
@@ -45,10 +45,10 @@ TEST(Escape, PosixCommand) {
   opts.platform = ESCAPE_PLATFORM_POSIX;
 
   // : and $ ninja escaped with $. Then Shell-escape backslashes and quotes.
-  EXPECT_EQ("a$:\\$ \\\"\\$$\\\\b", EscapeString("a: \"$\\b", opts, NULL));
+  EXPECT_EQ("a$:\\$ \\\"\\$$\\\\b", EscapeString("a: \"$\\b", opts, nullptr));
 
   // Some more generic shell chars.
-  EXPECT_EQ("a_\\;\\<\\*b", EscapeString("a_;<*b", opts, NULL));
+  EXPECT_EQ("a_\\;\\<\\*b", EscapeString("a_;<*b", opts, nullptr));
 }
 
 TEST(Escape, NinjaPreformatted) {
@@ -56,5 +56,5 @@ TEST(Escape, NinjaPreformatted) {
   opts.mode = ESCAPE_NINJA_PREFORMATTED_COMMAND;
 
   // Only $ is escaped.
-  EXPECT_EQ("a: \"$$\\b<;", EscapeString("a: \"$\\b<;", opts, NULL));
+  EXPECT_EQ("a: \"$$\\b<;", EscapeString("a: \"$\\b<;", opts, nullptr));
 }