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

ui/base/resource/data_pack.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.
 
 // DataPack represents a read-only view onto an on-disk file that contains
 // (key, value) pairs of data.  It's used to store static resources like
 // translation strings and images.
 
 #ifndef UI_BASE_RESOURCE_DATA_PACK_H_
 #define UI_BASE_RESOURCE_DATA_PACK_H_
@@ skipping 15 matching lines @@
 }
 
 namespace file_util {
 class MemoryMappedFile;
 }
 
 namespace ui {
 
 class UI_EXPORT DataPack : public ResourceHandle {
  public:
-  DataPack(ui::ScaleFactor scale_factor);
+  explicit DataPack(ui::ScaleFactor scale_factor);
   virtual ~DataPack();
 
   // Load a pack file from |path|, returning false on error.
   bool LoadFromPath(const FilePath& path);
 
   // Loads a pack file from |file|, returning false on error.
   bool LoadFromFile(base::PlatformFile file);
 
   // Writes a pack file containing |resources| to |path|. If there are any
   // text resources to be written, their encoding must already agree to the
@@ skipping 28 matching lines @@
   // The scale of the image in this resource pack relative to images in the 1x
   // resource pak.
   ui::ScaleFactor scale_factor_;
 
   DISALLOW_COPY_AND_ASSIGN(DataPack);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_RESOURCE_DATA_PACK_H_