Coverity: Fix several pass-by-values.

chrome/test/base/chrome_process_util.cc

 // Copyright (c) 2011 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.
 
 #include "chrome/test/base/chrome_process_util.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 22 matching lines @@
     base::KillProcess(handle, content::RESULT_CODE_KILLED, true);
     base::CloseProcessHandle(handle);
   }
 }
 
 class ChildProcessFilter : public base::ProcessFilter {
  public:
   explicit ChildProcessFilter(base::ProcessId parent_pid)
       : parent_pids_(&parent_pid, (&parent_pid) + 1) {}
 
-  explicit ChildProcessFilter(std::vector<base::ProcessId> parent_pids)
+  explicit ChildProcessFilter(const std::vector<base::ProcessId>& parent_pids)
       : parent_pids_(parent_pids.begin(), parent_pids.end()) {}
 
   virtual bool Includes(const base::ProcessEntry& entry) const {
     return parent_pids_.find(entry.parent_pid()) != parent_pids_.end();
   }
 
  private:
   const std::set<base::ProcessId> parent_pids_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildProcessFilter);
@@ skipping 97 matching lines @@
     base::ProcessHandle process) {
 #if !defined(OS_MACOSX)
   process_metrics_.reset(
       base::ProcessMetrics::CreateProcessMetrics(process));
 #else
   process_metrics_.reset(
       base::ProcessMetrics::CreateProcessMetrics(process, NULL));
 #endif
   process_handle_ = process;
 }