Support for source_target_relative expansion in GN

tools/gn/substitution_type.h

 // Copyright 2014 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_SUBSTITUTION_TYPE_H_
 #define TOOLS_GN_SUBSTITUTION_TYPE_H_
 
 #include <vector>
 
 class Err;
@@ skipping 12 matching lines @@
   SUBSTITUTION_SOURCE = SUBSTITUTION_FIRST_PATTERN,  // {{source}}
   SUBSTITUTION_OUTPUT,  // {{output}}
 
   // Valid for all compiler tools.
   SUBSTITUTION_SOURCE_NAME_PART,  // {{source_name_part}}
   SUBSTITUTION_SOURCE_FILE_PART,  // {{source_file_part}}
   SUBSTITUTION_SOURCE_DIR,  // {{source_dir}}
   SUBSTITUTION_SOURCE_ROOT_RELATIVE_DIR,  // {{root_relative_dir}}
   SUBSTITUTION_SOURCE_GEN_DIR,  // {{source_gen_dir}}
   SUBSTITUTION_SOURCE_OUT_DIR,  // {{source_out_dir}}
+  SUBSTITUTION_SOURCE_TARGET_RELATIVE,  // {{source_target_relative}}
 
   // Valid for all compiler and linker tools. These depend on the target and
   // do not vary on a per-file basis.
   SUBSTITUTION_LABEL,  // {{label}}
   SUBSTITUTION_LABEL_NAME,  // {{label_name}}
   SUBSTITUTION_ROOT_GEN_DIR,  // {{root_gen_dir}}
   SUBSTITUTION_ROOT_OUT_DIR,  // {{root_out_dir}}
   SUBSTITUTION_TARGET_GEN_DIR,  // {{target_gen_dir}}
   SUBSTITUTION_TARGET_OUT_DIR,  // {{target_out_dir}}
   SUBSTITUTION_TARGET_OUTPUT_NAME,  // {{target_output_name}}
@@ skipping 85 matching lines @@
 bool IsValidCompileXCassetsSubstitution(SubstitutionType type);
 
 // Like the "IsValid..." version above but checks a list of types and sets a
 // an error blaming the given source if the test fails.
 bool EnsureValidSourcesSubstitutions(
     const std::vector<SubstitutionType>& types,
     const ParseNode* origin,
     Err* err);
 
 #endif  // TOOLS_GN_SUBSTITUTION_TYPE_H_