Improve GN public header file checking

tools/gn/header_checker_unittest.cc

Index: tools/gn/header_checker_unittest.cc
diff --git a/tools/gn/header_checker_unittest.cc b/tools/gn/header_checker_unittest.cc
index 90e4165529c8db9be36a9b240ce351d72a1718b8..05c5f647c5cd4b717a381ef01a405d5f0c04737e 100644
--- a/tools/gn/header_checker_unittest.cc
+++ b/tools/gn/header_checker_unittest.cc
@@ -15,12 +15,17 @@ namespace {
 class HeaderCheckerTest : public testing::Test {
  public:
   HeaderCheckerTest()
-      : a_(setup_.settings(), Label(SourceDir("//"), "a")),
-        b_(setup_.settings(), Label(SourceDir("//"), "a")),
-        c_(setup_.settings(), Label(SourceDir("//"), "c")) {
+      : a_(setup_.settings(), Label(SourceDir("//a/"), "a")),
+        b_(setup_.settings(), Label(SourceDir("//b/"), "a")),
+        c_(setup_.settings(), Label(SourceDir("//c/"), "c")) {
     a_.deps().push_back(LabelTargetPair(&b_));
     b_.deps().push_back(LabelTargetPair(&c_));
 
+    // Start with all public visibility.
+    a_.visibility().SetPublic();
+    b_.visibility().SetPublic();
+    c_.visibility().SetPublic();
+
     targets_.push_back(&a_);
     targets_.push_back(&b_);
     targets_.push_back(&c_);
@@ -53,6 +58,10 @@ TEST_F(HeaderCheckerTest, IsDependencyOf) {
 }
 
 TEST_F(HeaderCheckerTest, CheckInclude) {
+  InputFile input_file(SourceFile("//some_file.cc"));
+  input_file.SetContents(std::string());
+  LocationRange range;  // Dummy value.
+
   // Add a disconnected target d with a header to check that you have to have
   // to depend on a target listing a header.
   Target d(setup_.settings(), Label(SourceDir("//"), "d"));
@@ -78,25 +87,31 @@ TEST_F(HeaderCheckerTest, CheckInclude) {
   // A file in target A can't include a header from D because A has no
   // dependency on D.
   Err err;
-  SourceFile source_file("//some_file.cc");
-  EXPECT_FALSE(checker->CheckInclude(&a_, source_file, d_header, &err));
+  EXPECT_FALSE(checker->CheckInclude(&a_, input_file, d_header, range, &err));
   EXPECT_TRUE(err.has_error());
 
   // A can include the public header in B.
   err = Err();
-  EXPECT_TRUE(checker->CheckInclude(&a_, source_file, b_public, &err));
+  EXPECT_TRUE(checker->CheckInclude(&a_, input_file, b_public, range, &err));
   EXPECT_FALSE(err.has_error());
 
   // Check A depending on the public and private headers in C.
   err = Err();
-  EXPECT_TRUE(checker->CheckInclude(&a_, source_file, c_public, &err));
+  EXPECT_TRUE(checker->CheckInclude(&a_, input_file, c_public, range, &err));
   EXPECT_FALSE(err.has_error());
-  EXPECT_FALSE(checker->CheckInclude(&a_, source_file, c_private, &err));
+  EXPECT_FALSE(checker->CheckInclude(&a_, input_file, c_private, range, &err));
   EXPECT_TRUE(err.has_error());
 
   // A can depend on a random file unknown to the build.
   err = Err();
-  EXPECT_TRUE(checker->CheckInclude(&a_, source_file, SourceFile("//random.h"),
-                                    &err));
+  EXPECT_TRUE(checker->CheckInclude(&a_, input_file, SourceFile("//random.h"),
+                                    range, &err));
   EXPECT_FALSE(err.has_error());
+
+  // If C is not visible from A, A can't include public headers even if there
+  // is a dependency path.
+  c_.visibility().SetPrivate(c_.label().dir());
+  err = Err();
+  EXPECT_FALSE(checker->CheckInclude(&a_, input_file, c_public, range, &err));
+  EXPECT_TRUE(err.has_error());
 }