Adds more BUILD.gns to ash

ash/common/test/ash_test.h

 // Copyright 2016 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 ASH_COMMON_TEST_ASH_TEST_H_
 #define ASH_COMMON_TEST_ASH_TEST_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 31 matching lines @@
   WmWindow* window_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowOwner);
 };
 
 // Base class for ash tests. This class calls through to AshTestImpl for the
 // real implementation. This class exists so that tests can be written to
 // ash/common and run in both mus and aura.
 //
 // The implementation of AshTestImpl that is used depends upon gn targets. To
-// use the aura backend depend on "//ash:ash_with_aura_test_support." The mus
-// backend is not provided as a separate link target.
+// use the aura backend depend on "//ash/test:ash_with_aura_test_support." The
+// mus backend is not provided as a separate link target.
 class AshTest : public testing::Test {
  public:
   AshTest();
   ~AshTest() override;
 
   // Returns the WmShelf for the primary display.
   static WmShelf* GetPrimaryShelf();
 
   bool SupportsMultipleDisplays() const;
 
@@ skipping 57 matching lines @@
 
  private:
   std::unique_ptr<AshTestImpl> test_impl_;
 
   DISALLOW_COPY_AND_ASSIGN(AshTest);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_TEST_ASH_TEST_H_