Add methods for hashing pairs of integer values.

cc/cc_tests.gyp

 # Copyright (c) 2012 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.
 
 {
   'variables': {
     'chromium_code': 0,
     'use_libcc_for_compositor%': 0,
     'cc_tests_source_files': [
+      'hash_pair_unittest.cc',
       'CCActiveAnimationTest.cpp',
       'CCDamageTrackerTest.cpp',
       'CCDelayBasedTimeSourceTest.cpp',
       'CCDrawQuadTest.cpp',
       'CCDelegatedRendererLayerImplTest.cpp',
       'CCFrameRateControllerTest.cpp',
       'CCHeadsUpDisplayTest.cpp',
       'CCKeyframedAnimationCurveTest.cpp',
       'CCLayerAnimationControllerTest.cpp',
       'CCLayerImplTest.cpp',
@@ skipping 128 matching lines @@
             '<@(cc_tests_support_files)',
             'test/test_webkit_platform.cc',
             'test/test_webkit_platform.h',
           ],
         },
       ],
     }],
   ],
 }