Move chrome zoom constants into their own file.

chrome/browser/chrome_page_zoom.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_CHROME_PAGE_ZOOM_H_
 #define CHROME_BROWSER_CHROME_PAGE_ZOOM_H_
 #pragma once
 
 #include <vector>
 
 namespace chrome_page_zoom {
 
-// Zoom factors supported by the browser.
-extern const double kPresetZoomFactors[];
-
-// Size of |kPresetZoomFactors|.
-extern const size_t kPresetZoomFactorsSize;
-
 // Return a sorted vector of zoom factors. The vector will consist of preset
 // values along with a custom value (if the custom value is not already
 // represented.)
 std::vector<double> PresetZoomFactors(double custom_factor);
 
 // Return a sorted vector of zoom levels. The vector will consist of preset
 // values along with a custom value (if the custom value is not already
 // represented.)
 std::vector<double> PresetZoomLevels(double custom_level);
 
 }  // namespace chrome_page_zoom
 
 #endif  // CHROME_BROWSER_CHROME_PAGE_ZOOM_H_