Follow macro invocations when checking if a violation happened in a .cc file.

tools/clang/plugins/ChromeClassTester.cpp

Index: tools/clang/plugins/ChromeClassTester.cpp
diff --git a/tools/clang/plugins/ChromeClassTester.cpp b/tools/clang/plugins/ChromeClassTester.cpp
index 8d0b22d0cce786dc2953c4fadf6647a59debbbc5..b39e14a0e2b08cfa8de907a4894c7af244cf1973 100644
--- a/tools/clang/plugins/ChromeClassTester.cpp
+++ b/tools/clang/plugins/ChromeClassTester.cpp
@@ -189,12 +189,31 @@ std::string ChromeClassTester::GetNamespace(const Decl* record) {
 
 bool ChromeClassTester::InImplementationFile(SourceLocation record_location) {
   std::string filename;
-  if (!GetFilename(record_location, &filename))
-    return false;
 
-  if (ends_with(filename, ".cc") || ends_with(filename, ".cpp") ||
-      ends_with(filename, ".mm")) {
-    return true;
+  if (options_.follow_macro_expansion) {
+    // If |record_location| is a macro, check the whole chain of expansions.
+    const SourceManager& source_manager = instance_.getSourceManager();
+    while (true) {
+      if (GetFilename(record_location, &filename)) {
+        if (ends_with(filename, ".cc") || ends_with(filename, ".cpp") ||
+            ends_with(filename, ".mm")) {
+          return true;
+        }
+      }
+      if (!record_location.isMacroID()) {
+        break;
+      }
+      record_location =
+          source_manager.getImmediateExpansionRange(record_location).first;
+    }
+  } else {
+    if (!GetFilename(record_location, &filename))
+      return false;
+
+    if (ends_with(filename, ".cc") || ends_with(filename, ".cpp") ||
+        ends_with(filename, ".mm")) {
+      return true;
+    }
   }
 
   return false;