Refactor GN source expansions.

tools/gn/filesystem_utils.cc

Index: tools/gn/filesystem_utils.cc
diff --git a/tools/gn/filesystem_utils.cc b/tools/gn/filesystem_utils.cc
index 097a2276b225003214253be93a479207a360c0c6..c1e3200209c49467ee80ad99fda10f299d2bd410 100644
--- a/tools/gn/filesystem_utils.cc
+++ b/tools/gn/filesystem_utils.cc
@@ -11,7 +11,6 @@
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
-#include "tools/gn/file_template.h"
 #include "tools/gn/location.h"
 #include "tools/gn/settings.h"
 #include "tools/gn/source_dir.h"
@@ -335,7 +334,6 @@ base::StringPiece FindLastDirComponent(const SourceDir& dir) {
 bool EnsureStringIsInOutputDir(const SourceDir& dir,
                                const std::string& str,
                                const Value& originating,
-                               bool allow_templates,
                                Err* err) {
   // This check will be wrong for all proper prefixes "e.g. "/output" will
   // match "/out" but we don't really care since this is just a sanity check.
@@ -343,14 +341,6 @@ bool EnsureStringIsInOutputDir(const SourceDir& dir,
   if (str.compare(0, dir_str.length(), dir_str) == 0)
     return true;  // Output directory is hardcoded.
 
-  if (allow_templates) {
-    // Allow the string to begin with any source expansion inside the output
-    // directory.
-    if (StartsWithASCII(str, FileTemplate::kSourceGenDir, true) ||
-        StartsWithASCII(str, FileTemplate::kSourceOutDir, true))
-      return true;
-  }
-
   *err = Err(originating, "File is not inside output directory.",
       "The given file should be in the output directory. Normally you would "
       "specify\n\"$target_out_dir/foo\" or "