Extract WebGraphicsContext3DImpl from webkit/common/gpu.

gpu/blink/gpu_blink.gyp

+# 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.
+
+{
+  'targets': [
+    {
+      # GN version: //gpu/blink
+      'target_name': 'gpu_blink',
+      'type': '<(component)',
+      'dependencies': [
+        '../../base/base.gyp:base',
+        '../../gpu/command_buffer/command_buffer.gyp:gles2_utils',
+        '../../gpu/gpu.gyp:command_buffer_common',
+        '../../gpu/gpu.gyp:gles2_c_lib',
+        '../../gpu/gpu.gyp:gles2_implementation',
+        '../../gpu/skia_bindings/skia_bindings.gyp:gpu_skia_bindings',
+        '../../third_party/WebKit/public/blink.gyp:blink',
+      ],
+      'defines': [
+        'GPU_BLINK_IMPLEMENTATION',
+      ],
+      # This sources list is duplicated in //gpu/blink/BUILD.gn
+      'sources': [
+        'gpu_blink_export.h',
+        'webgraphicscontext3d_impl.cc',
+        'webgraphicscontext3d_impl.h',
+      ],
+    },
+  ]
+}