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

content/renderer/pepper/pepper_file_chooser_host.cc

 // 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.
 
 #include "content/renderer/pepper/pepper_file_chooser_host.h"
 
 #include "base/file_path.h"
 #include "base/utf_string_conversions.h"
 #include "content/public/renderer/renderer_ppapi_host.h"
 #include "content/renderer/render_view_impl.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/host/dispatch_host_message.h"
 #include "ppapi/host/ppapi_host.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/ppb_file_ref_proxy.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebCString.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFileChooserCompletion.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFileChooserParams.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebVector.h"
 #include "webkit/plugins/ppapi/ppb_file_ref_impl.h"
 
 namespace content {
 
 class PepperFileChooserHost::CompletionHandler
     : public WebKit::WebFileChooserCompletion {
  public:
-  CompletionHandler(const base::WeakPtr<PepperFileChooserHost>& host)
+  explicit CompletionHandler(const base::WeakPtr<PepperFileChooserHost>& host)
       : host_(host) {
   }
 
   virtual ~CompletionHandler() {}
 
   virtual void didChooseFile(
       const WebKit::WebVector<WebKit::WebString>& file_names) {
     if (host_) {
       std::vector<PepperFileChooserHost::ChosenFileInfo> files;
       for (size_t i = 0; i < file_names.size(); i++) {
@@ skipping 123 matching lines @@
     delete handler_;
     handler_ = NULL;
     return PP_ERROR_NOACCESS;
   }
 
   reply_context_ = context->MakeReplyMessageContext();
   return PP_OK_COMPLETIONPENDING;
 }
 
 }  // namespace content
-