Reference written files relatively when possible.

tools/gn/filesystem_utils.h

 // Copyright (c) 2013 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.
 
 #ifndef TOOLS_GN_FILESYSTEM_UTILS_H_
 #define TOOLS_GN_FILESYSTEM_UTILS_H_
 
 #include <string>
 
 #include "base/files/file_path.h"
@@ skipping 82 matching lines @@
 //
 // The origin will be blamed in the error.
 //
 // If the file isn't in the dir, returns false and sets the error. Otherwise
 // returns true and leaves the error untouched.
 bool EnsureStringIsInOutputDir(const SourceDir& output_dir,
                                const std::string& str,
                                const ParseNode* origin,
                                Err* err);
 
+// If the file isn't in the dir, returns the empty string and sets the error.
+// Otherwise returns the short output name and leaves the error untouched.
+base::FilePath::StringType ComputeStringInOutputDir(const SourceDir& output_dir,
+                                                    const SourceFile& file,
+                                                    Err* err);
+
+
 // ----------------------------------------------------------------------------
 
 // Returns true if the input string is absolute. Double-slashes at the
 // beginning are treated as source-relative paths. On Windows, this handles
 // paths of both the native format: "C:/foo" and ours "/C:/foo"
 bool IsPathAbsolute(const base::StringPiece& path);
 
 // Given an absolute path, checks to see if is it is inside the source root.
 // If it is, fills a source-absolute path into the given output and returns
 // true. If it isn't, clears the dest and returns false.
@@ skipping 75 matching lines @@
 
 SourceDir GetTargetOutputDir(const Target* target);
 OutputFile GetTargetOutputDirAsOutputFile(const Target* target);
 SourceDir GetTargetGenDir(const Target* target);
 OutputFile GetTargetGenDirAsOutputFile(const Target* target);
 
 SourceDir GetCurrentOutputDir(const Scope* scope);
 SourceDir GetCurrentGenDir(const Scope* scope);
 
 #endif  // TOOLS_GN_FILESYSTEM_UTILS_H_