chrome: Cleanup class/struct forward declarations

chrome/app/chrome_crash_reporter_client.h

 // Copyright 2013 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 CHROME_APP_CHROME_CRASH_REPORTER_CLIENT_H_
 #define CHROME_APP_CHROME_CRASH_REPORTER_CLIENT_H_
 
 #if !defined(OS_WIN)
 
 #include <stddef.h>
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "components/crash/content/app/crash_reporter_client.h"
 
-namespace browser_watcher {
-class CrashReportingMetrics;
-}  // namespace browser_watcher
-
 class ChromeCrashReporterClient : public crash_reporter::CrashReporterClient {
  public:
   ChromeCrashReporterClient();
   ~ChromeCrashReporterClient() override;
 
   // crash_reporter::CrashReporterClient implementation.
 #if !defined(OS_MACOSX)
   void SetCrashReporterClientIdFromGUID(
       const std::string& client_guid) override;
 #endif
@@ skipping 22 matching lines @@
 
   bool EnableBreakpadForProcess(const std::string& process_type) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ChromeCrashReporterClient);
 };
 
 #endif  // OS_WIN
 
 #endif  // CHROME_APP_CHROME_CRASH_REPORTER_CLIENT_H_