Add crashpad_info, MachOImageAnnotationsReader, and its test

snapshot/mac/process_types/crashpad_info.proctype

Index: snapshot/mac/process_types/crashpad_info.proctype
diff --git a/snapshot/mac/process_types/crashpad_info.proctype b/snapshot/mac/process_types/crashpad_info.proctype
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+++ b/snapshot/mac/process_types/crashpad_info.proctype
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+// 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.
+
+// The file corresponds to Crashpad’s client/crashpad_info.h.
+//
+// This file is intended to be included multiple times in the same translation
+// unit, so #include guards are intentionally absent.
+//
+// This file is included by snapshot/mac/process_types.h and
+// snapshot/mac/process_types.cc to produce process type struct definitions and
+// accessors.
+
+// Client Mach-O images will contain a __DATA,__crashpad_info section formatted
+// according to this structure.
+PROCESS_TYPE_STRUCT_BEGIN(CrashpadInfo)
+  PROCESS_TYPE_STRUCT_MEMBER(uint32_t, signature)
+  PROCESS_TYPE_STRUCT_MEMBER(uint32_t, size)
+  PROCESS_TYPE_STRUCT_MEMBER(uint32_t, version)
+  PROCESS_TYPE_STRUCT_MEMBER(uint32_t, padding_0)
+
+  // SimpleStringDictionary*
+  PROCESS_TYPE_STRUCT_MEMBER(Pointer, simple_annotations)
+PROCESS_TYPE_STRUCT_END(CrashpadInfo)