Restructure the ipc_fuzzer directory.

tools/ipc_fuzzer/fuzzer/mutator.h

 // Copyright 2015 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.
 
 #ifndef TOOLS_IPC_FUZZER_MUTATE_MUTATOR_H_
 #define TOOLS_IPC_FUZZER_MUTATE_MUTATOR_H_
 
 #include <string>
 
-#include "tools/ipc_fuzzer/mutate/fuzzer.h"
+#include "tools/ipc_fuzzer/fuzzer/fuzzer.h"
 
 namespace ipc_fuzzer {
 
 class Mutator : public Fuzzer {
  public:
   explicit Mutator(unsigned int frequency) : frequency_(frequency) {}
   virtual ~Mutator() {}
 
   void FuzzBool(bool* value) override;
   void FuzzInt(int* value) override;
@@ skipping 14 matching lines @@
   bool ShouldGenerate() override;
 
  private:
   // TODO(mbarbella): Use double frequencies.
   unsigned int frequency_;
 };
 
 }  // namespace ipc_fuzzer
 
 #endif  // TOOLS_IPC_FUZZER_MUTATE_MUTATOR_H_