Add a //nogncheck anntation to GN include checker

tools/gn/c_include_iterator_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/c_include_iterator.h"
 #include "tools/gn/input_file.h"
 #include "tools/gn/location.h"
 
 namespace {
@@ skipping 11 matching lines @@
 TEST(CIncludeIterator, Basic) {
   std::string buffer;
   buffer.append("// Some comment\n");
   buffer.append("\n");
   buffer.append("#include \"foo/bar.h\"\n");
   buffer.append("\n");
   buffer.append("#include <stdio.h>\n");
   buffer.append("\n");
   buffer.append(" #include \"foo/baz.h\"\n");  // Leading whitespace
   buffer.append("#include \"la/deda.h\"\n");
+  // Line annotated with "// nogncheck"
+  buffer.append("#include \"should_be_skipped.h\"  // nogncheck\n");
   buffer.append("#import \"weird_mac_import.h\"\n");
   buffer.append("\n");
   buffer.append("void SomeCode() {\n");
 
   InputFile file(SourceFile("//foo.cc"));
   file.SetContents(buffer);
 
   CIncludeIterator iter(&file);
 
   base::StringPiece contents;
   LocationRange range;
   EXPECT_TRUE(iter.GetNextIncludeString(&contents, &range));
   EXPECT_EQ("foo/bar.h", contents);
   EXPECT_TRUE(RangeIs(range, 3, 11, 20)) << range.begin().Describe(true);
 
   EXPECT_TRUE(iter.GetNextIncludeString(&contents, &range));
   EXPECT_EQ("foo/baz.h", contents);
   EXPECT_TRUE(RangeIs(range, 7, 12, 21)) << range.begin().Describe(true);
 
   EXPECT_TRUE(iter.GetNextIncludeString(&contents, &range));
   EXPECT_EQ("la/deda.h", contents);
   EXPECT_TRUE(RangeIs(range, 8, 11, 20)) << range.begin().Describe(true);
 
+  // The line annotated with "nogncheck" should be skipped.
+
   EXPECT_TRUE(iter.GetNextIncludeString(&contents, &range));
   EXPECT_EQ("weird_mac_import.h", contents);
-  EXPECT_TRUE(RangeIs(range, 9, 10, 28)) << range.begin().Describe(true);
+  EXPECT_TRUE(RangeIs(range, 10, 10, 28)) << range.begin().Describe(true);
 
   EXPECT_FALSE(iter.GetNextIncludeString(&contents, &range));
 }
 
 // Tests that we don't search for includes indefinitely.
 TEST(CIncludeIterator, GiveUp) {
   std::string buffer;
   for (size_t i = 0; i < 1000; i++)
     buffer.append("x\n");
   buffer.append("#include \"foo/bar.h\"\n");
@@ skipping 53 matching lines @@
   base::StringPiece contents;
   LocationRange range;
 
   CIncludeIterator iter(&file);
   for (size_t group = 0; group < kGroupCount; group++) {
     EXPECT_TRUE(iter.GetNextIncludeString(&contents, &range));
     EXPECT_EQ(include, contents.as_string());
   }
   EXPECT_FALSE(iter.GetNextIncludeString(&contents, &range));
 }