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

chrome/browser/extensions/api/serial/serial_apitest.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 <deque>
 #include <string>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/extensions/api/serial/serial_api.h"
@@ skipping 31 matching lines @@
     SetResult(ports);
     SendResponse(true);
     return true;
   }
  protected:
   virtual ~FakeSerialGetPortsFunction() {}
 };
 
 class FakeEchoSerialConnection : public SerialConnection {
  public:
-  explicit FakeEchoSerialConnection(
-      const std::string& port,
-      int bitrate,
-      const std::string& owner_extension_id)
+  FakeEchoSerialConnection(const std::string& port, int bitrate,
+                           const std::string& owner_extension_id)
       : SerialConnection(port, bitrate, owner_extension_id),
         opened_(true) {
     Flush();
     opened_ = false;
   }
 
   virtual ~FakeEchoSerialConnection() {
   }
 
   virtual bool Open() {
@@ skipping 114 matching lines @@
 
   ASSERT_TRUE(RunExtensionTest("serial/api")) << message_;
 }
 
 IN_PROC_BROWSER_TEST_F(SerialApiTest, SerialRealHardware) {
   ResultCatcher catcher;
   catcher.RestrictToProfile(browser()->profile());
 
   ASSERT_TRUE(RunExtensionTest("serial/real_hardware")) << message_;
 }