Don't inherit source sets across static libs in GN.

tools/gn/target.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_TARGET_H_
 #define TOOLS_GN_TARGET_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 180 matching lines @@
   LabelTargetVector datadeps_;
 
   LabelConfigVector configs_;
   LabelConfigVector all_dependent_configs_;
   LabelConfigVector direct_dependent_configs_;
   LabelTargetVector forward_dependent_configs_;
 
   bool external_;
 
   // Static libraries and source sets from transitive deps. These things need
-  // to be linked only with the end target (executable, shared library). These
-  // do not get pushed beyond shared library boundaries.
+  // to be linked only with the end target (executable, shared library). Source
+  // sets do not get pushed beyond static library boundaries, and neither
+  // source sets nor static libraries get pushed beyond sahred library
+  // boundaries.
   std::set<const Target*> inherited_libraries_;
 
   // These libs and dirs are inherited from statically linked deps and all
   // configs applying to this target.
   OrderedSet<SourceDir> all_lib_dirs_;
   OrderedSet<std::string> all_libs_;
 
   // All hard deps from this target and all dependencies. Filled in when this
   // target is marked resolved. This will not include the current target.
   std::set<const Target*> recursive_hard_deps_;
 
   ConfigValues config_values_;  // Used for all binary targets.
   ActionValues action_values_;  // Used for action[_foreach] targets.
 
   DISALLOW_COPY_AND_ASSIGN(Target);
 };
 
 #endif  // TOOLS_GN_TARGET_H_