Implement tracking of BUILD.gn files used to define target, toolchain or

tools/gn/item.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_ITEM_H_
 #define TOOLS_GN_ITEM_H_
 
+#include <set>
 #include <string>
 
 #include "tools/gn/label.h"
+#include "tools/gn/source_file.h"
 #include "tools/gn/visibility.h"
 
 class Config;
 class ParseNode;
 class Pool;
 class Settings;
 class Target;
 class Toolchain;
 
 // A named item (target, config, etc.) that participates in the dependency
 // graph.
 class Item {
  public:
-  Item(const Settings* settings, const Label& label);
+  Item(const Settings* settings,
+       const Label& label,
+       const std::set<uint32_t>& source_files_hashes);
   virtual ~Item();
 
   const Settings* settings() const { return settings_; }
 
   // This is guaranteed to never change after construction so this can be
   // accessed from any thread with no locking once the item is constructed.
   const Label& label() const { return label_; }
 
   const ParseNode* defined_from() const { return defined_from_; }
   void set_defined_from(const ParseNode* df) { defined_from_ = df; }
@@ skipping 13 matching lines @@
 
   // Returns a name like "target" or "config" for the type of item this is, to
   // be used in logging and error messages.
   std::string GetItemTypeName() const;
 
   // Called when this item is resolved, meaning it and all of its dependents
   // have no unresolved deps. Returns true on success. Sets the error and
   // returns false on failure.
   virtual bool OnResolved(Err* err);
 
+  const std::set<uint32_t>& source_files_hashes() const {
+    return source_files_hashes_;
+  }
+
  private:
   const Settings* settings_;
   Label label_;
   const ParseNode* defined_from_;
 
   Visibility visibility_;
+  std::set<uint32_t> source_files_hashes_;
 };
 
 #endif  // TOOLS_GN_ITEM_H_