Compute pageScaleFactor on page so that fixed layout page fits width of window.

content/common/content_constants.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.
 
 // A handful of resource-like constants related to the Content application.
 
 #ifndef CONTENT_COMMON_CHROME_CONSTANTS_H_
 #define CONTENT_COMMON_CHROME_CONSTANTS_H_
 #pragma once
 
@@ skipping 12 matching lines @@
 
 // The maximum number of characters in the URL that we're willing to accept
 // in the browser process. It is set low enough to avoid damage to the browser
 // but high enough that a web site can abuse location.hash for a little storage.
 // We have different values for "max accepted" and "max displayed" because
 // a data: URI may be legitimately massive, but the full URI would kill all
 // known operating systems if you dropped it into a UI control.
 extern const size_t kMaxURLChars;
 extern const size_t kMaxURLDisplayChars;
 
+// Min and max scaling factors for pinch-zooming on touch platforms.
+extern const float kMinPageScaleFactor;
+extern const float kMaxPageScaleFactor;
+
 }  // namespace content
 
 #endif  // CONTENT_COMMON_CHROME_CONSTANTS_H_