Add public deps to GN

tools/gn/deps_iterator.h

Index: tools/gn/deps_iterator.h
diff --git a/tools/gn/deps_iterator.h b/tools/gn/deps_iterator.h
new file mode 100644
index 0000000000000000000000000000000000000000..5fc3c01e019f33eff2e9714bc4fb9fbf8d6d1fd4
--- /dev/null
+++ b/tools/gn/deps_iterator.h
@@ -0,0 +1,61 @@
+// 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_DEPS_ITERATOR_H_
+#define TOOLS_GN_DEPS_ITERATOR_H_
+
+#include "base/basictypes.h"
+#include "tools/gn/label_ptr.h"
+
+class Target;
+
+// Iterates over the deps of a target.
+//
+// Since there are multiple kinds of deps, this iterator allows looping over
+// each one in one loop.
+class DepsIterator {
+ public:
+  enum LinkedOnly {
+    LINKED_ONLY,
+  };
+
+  // Iterate over public, private, and data deps.
+  explicit DepsIterator(const Target* t);
+
+  // Iterate over the public and private linked deps, but not the data deps.
+  DepsIterator(const Target* t, LinkedOnly);
+
+  // Returns true when there are no more targets.
+  bool done() const {
+    return !vect_stack_[0];
+  }
+
+  // Advance to the next position. This assumes !done().
+  //
+  // For internal use, this function tolerates an initial index equal to the
+  // length of the current vector. In this case, it will advance to the next
+  // one.
+  void Advance();
+
+  // The current dependency.
+  const LabelTargetPair& pair() const {
+    DCHECK_LT(current_index_, vect_stack_[0]->size());
+    return (*vect_stack_[0])[current_index_];
+  }
+
+  // The pointer to the current dependency.
+  const Target* target() const { return pair().ptr; }
+
+  // The label of the current dependency.
+  const Label& label() const { return pair().label; }
+
+ private:
+  const LabelTargetVector* vect_stack_[3];
+
+  size_t current_index_;
+
+  DISALLOW_COPY_AND_ASSIGN(DepsIterator);
+};
+
+#endif  // TOOLS_GN_DEPS_ITERATOR_H_