GN: Use implicit dependency for binary input deps

tools/gn/ninja_target_writer_unittest.cc

 // 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.
 
 #include <sstream>
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/ninja_target_writer.h"
 #include "tools/gn/target.h"
 #include "tools/gn/test_with_scope.h"
@@ skipping 67 matching lines @@
     EXPECT_EQ("", stream.str());
   }
 
   // Input deps for the target (should depend on the base).
   {
     std::ostringstream stream;
     TestingNinjaTargetWriter writer(&target, setup.toolchain(), stream);
     OutputFile dep =
         writer.WriteInputDepsStampAndGetDep(std::vector<const Target*>());
 
-    // Since there is more than one dependency, a stamp file will be returned
-    // and the rule for the stamp file will be written to the stream.
-    EXPECT_EQ("obj/foo/target.inputdeps.stamp", dep.value());
-    EXPECT_EQ("build obj/foo/target.inputdeps.stamp: stamp "
-                  "../../foo/input.txt obj/foo/base.stamp\n",
-              stream.str());
+    // Since there is only one dependency, a stamp file will be returned
+    // directly without writing any additional rules.
+    EXPECT_EQ("obj/foo/base.stamp", dep.value());
   }
 
   // Input deps for action which should depend on the base since its a hard dep
   // that is a (indirect) dependency, as well as the the action source.
   {
     std::ostringstream stream;
     TestingNinjaTargetWriter writer(&action, setup.toolchain(), stream);
     OutputFile dep =
         writer.WriteInputDepsStampAndGetDep(std::vector<const Target*>());
 
@@ skipping 29 matching lines @@
   std::ostringstream stream;
   TestingNinjaTargetWriter writer(&target, setup.toolchain(), stream);
   OutputFile dep =
       writer.WriteInputDepsStampAndGetDep(std::vector<const Target*>());
 
   // Since there is more than one dependency, a stamp file will be returned
   // and the rule for the stamp file will be written to the stream.
   EXPECT_EQ("obj/foo/setup.stamp", dep.value());
   EXPECT_EQ("", stream.str());
 }