Add CaptureContext and its test

client/client.gyp

+# Copyright 2014 The Crashpad Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+{
+  'targets': [
+    {
+      'target_name': 'client',
+      'type': 'static_library',
+      'dependencies': [
+        '../third_party/mini_chromium/mini_chromium/base/base.gyp:base',
+      ],
+      'include_dirs': [
+        '..',
+      ],
+      'sources': [
+        'capture_context_mac.h',
+        'capture_context_mac.S',
+      ],
+    },
+    {
+      'target_name': 'client_test',
+      'type': 'executable',
+      'dependencies': [
+        'client',
+        '../third_party/gtest/gtest.gyp:gtest',
+        '../third_party/gtest/gtest.gyp:gtest_main',
+        '../third_party/mini_chromium/mini_chromium/base/base.gyp:base',
+      ],
+      'include_dirs': [
+        '..',
+      ],
+      'sources': [
+        'capture_context_mac_test.cc',
+      ],
+    },
+  ],
+}