win: Add implementation of system_snapshot for Windows

snapshot/win/process_reader_win.h

Index: snapshot/win/process_reader_win.h
diff --git a/snapshot/win/process_reader_win.h b/snapshot/win/process_reader_win.h
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+// Copyright 2015 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.
+
+#ifndef CRASHPAD_SNAPSHOT_WIN_PROCESS_READER_WIN_H_
+#define CRASHPAD_SNAPSHOT_WIN_PROCESS_READER_WIN_H_
+
+#include <windows.h>
+
+#include "util/misc/initialization_state_dcheck.h"
+
+namespace crashpad {
+
+//! \brief Accesses information about another process, identified by a HANDLE.
+class ProcessReaderWin {
+ public:
+  ProcessReaderWin();
+  ~ProcessReaderWin();
+
+  //! \brief Initializes this object. This method must be called before any
+  //!     other.
+  //!
+  //! \param[in] process Process handle, must have PROCESS_QUERY_INFORMATION,
+  //!     PROCESS_VM_READ, and PROCESS_DUP_HANDLE access.
+  //!
+  //! \return `true` on success, indicating that this object will respond
+  //!     validly to further method calls. `false` on failure. On failure, no
+  //!     further method calls should be made.
+  bool Initialize(HANDLE process);
+
+  //! \return `true` if the target task is a 64-bit process.
+  bool Is64Bit() const { return is_64_bit_; }
+
+ private:
+  bool is_64_bit_;
+  InitializationStateDcheck initialized_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProcessReaderWin);
+};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_SNAPSHOT_WIN_PROCESS_READER_WIN_H_