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

content/common/gpu/media/mac_video_decode_accelerator.mm

 // 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/common/gpu/media/mac_video_decode_accelerator.h"
 
 #include "base/bind.h"
 #include "base/file_path.h"
 #import "base/mac/foundation_util.h"
 #import "base/memory/ref_counted_memory.h"
@@ skipping 16 matching lines @@
       return ret_val;                                              \
     }                                                              \
   } while (0)
 
 namespace {
 
 enum { kNumPictureBuffers = 4 };
 
 class ScopedContextSetter {
  public:
-  ScopedContextSetter(CGLContextObj context)
+  explicit ScopedContextSetter(CGLContextObj context)
       : old_context_(NULL),
         did_succeed_(false) {
     old_context_ = CGLGetCurrentContext();
     did_succeed_ = CGLSetCurrentContext(context) == kCGLNoError;
   }
 
   ~ScopedContextSetter() {
     if (did_succeed_)
       CGLSetCurrentContext(old_context_);
   }
@@ skipping 333 matching lines @@
 MacVideoDecodeAccelerator::UsedPictureInfo::~UsedPictureInfo() {
 }
 
 MacVideoDecodeAccelerator::DecodedImageInfo::DecodedImageInfo() {
 }
 
 MacVideoDecodeAccelerator::DecodedImageInfo::~DecodedImageInfo() {
 }
 
 }  // namespace content