Add missing (and remove superfluous) 'explicit' from constructors.

rlz/lib/rlz_lib.h

 // Copyright (c) 2012 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.
 //
 // A library to manage RLZ information for access-points shared
 // across different client applications.
 //
 // All functions return true on success and false on error.
 // This implemenation is thread safe.
 
@@ skipping 303 matching lines @@
 //  rlz_lib::RecordProductEvent(rlz_lib::DESKTOP, rlz_lib::GD_DESKBAND,
 //                              rlz_lib::INSTALL);
 //
 // In particular, this affects the recording of stateful events and the sending
 // of financial pings.  In the former case, a stateful event recorded while
 // scoped to a supplementary brand will be recorded again when scoped to a
 // different supplementary brand (or not scoped at all).  In the latter case,
 // the time skip check is specific to each supplementary brand.
 class SupplementaryBranding {
  public:
-  SupplementaryBranding(const char* brand);
+  explicit SupplementaryBranding(const char* brand);
   ~SupplementaryBranding();
 
   static const std::string& GetBrand();
 
  private:
   ScopedRlzValueStoreLock* lock_;
 };
 
 }  // namespace rlz_lib
 
 #endif  // RLZ_LIB_RLZ_LIB_H_