Add more phony rules to GN build

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 74 matching lines @@
 // Returns true if the given path ends with a slash.
 bool EndsWithSlash(const std::string& s);
 
 // Path parts -----------------------------------------------------------------
 
 // Returns a string piece pointing into the input string identifying the
 // directory name of the given path, including the last slash. Note that the
 // input pointer must outlive the output.
 base::StringPiece FindDir(const std::string* path);
 
+// Returns the substring identifying the last component of the dir, or the
+// empty substring if none. For example "//foo/bar/" -> "bar".
+base::StringPiece FindLastDirComponent(const SourceDir& dir);
+
 // Verifies that the given string references a file inside of the given
 // directory. This is pretty stupid and doesn't handle "." and "..", etc.,
 // it is designed for a sanity check to keep people from writing output files
 // to the source directory accidentally.
 //
 // The originating value 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& dir,
@@ skipping 64 matching lines @@
 SourceDir GetOutputDirForSourceDir(const Settings* settings,
                                    const SourceDir& source_dir);
 SourceDir GetGenDirForSourceDir(const Settings* settings,
                                 const SourceDir& source_dir);
 SourceDir GetTargetOutputDir(const Target* target);
 SourceDir GetTargetGenDir(const Target* target);
 SourceDir GetCurrentOutputDir(const Scope* scope);
 SourceDir GetCurrentGenDir(const Scope* scope);
 
 #endif  // TOOLS_GN_FILESYSTEM_UTILS_H_