minidump: Use forward declarations in more places

minidump/minidump_exception_writer.h

 // 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.
 
 #ifndef CRASHPAD_MINIDUMP_MINIDUMP_EXCEPTION_WRITER_H_
 #define CRASHPAD_MINIDUMP_MINIDUMP_EXCEPTION_WRITER_H_
 
 #include <dbghelp.h>
 #include <stdint.h>
-#include <sys/types.h>
 
 #include <vector>
 
 #include "base/basictypes.h"
-#include "minidump/minidump_context_writer.h"
 #include "minidump/minidump_stream_writer.h"
-#include "util/file/file_writer.h"
 
 namespace crashpad {
 
+class MinidumpContextWriter;
+
 //! \brief The writer for a MINIDUMP_EXCEPTION_STREAM stream in a minidump file.
 class MinidumpExceptionWriter final : public internal::MinidumpStreamWriter {
  public:
   MinidumpExceptionWriter();
   ~MinidumpExceptionWriter() {}
 
   //! \brief Arranges for MINIDUMP_EXCEPTION_STREAM::ThreadContext to point to
   //!     the CPU context to be written by \a context.
   //!
   //! A context is required in all MINIDUMP_EXCEPTION_STREAM objects.
@@ skipping 56 matching lines @@
  private:
   MINIDUMP_EXCEPTION_STREAM exception_;
   MinidumpContextWriter* context_;  // weak
 
   DISALLOW_COPY_AND_ASSIGN(MinidumpExceptionWriter);
 };
 
 }  // namespace crashpad
 
 #endif  // CRASHPAD_MINIDUMP_MINIDUMP_EXCEPTION_WRITER_H_