Don't let rounding prematurely influence document size when printing

third_party/WebKit/Source/core/page/PrintContext.cpp

 /*
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2007 Apple Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 276 matching lines @@
     return String("pageProperty() unimplemented for: ") + propertyName;
 }
 
 bool PrintContext::isPageBoxVisible(LocalFrame* frame, int pageNumber)
 {
     return frame->document()->isPageBoxVisible(pageNumber);
 }
 
 String PrintContext::pageSizeAndMarginsInPixels(LocalFrame* frame, int pageNumber, int width, int height, int marginTop, int marginRight, int marginBottom, int marginLeft)
 {
-    IntSize pageSize(width, height);
+    FloatSize pageSize(width, height);
     frame->document()->pageSizeAndMarginsInPixels(pageNumber, pageSize, marginTop, marginRight, marginBottom, marginLeft);
 
-    return "(" + String::number(pageSize.width()) + ", " + String::number(pageSize.height()) + ") " +
+    return "(" + String::number(floor(pageSize.width())) + ", " + String::number(floor(pageSize.height())) + ") " +

[rhogan, 2016/07/13 18:27:13]

This is the other user, exposed via V8 bindings. I will snap to pixels here, as
you say flooring is wrong.

         String::number(marginTop) + ' ' + String::number(marginRight) + ' ' + String::number(marginBottom) + ' ' + String::number(marginLeft);
 }
 
 int PrintContext::numberOfPages(LocalFrame* frame, const FloatSize& pageSizeInPixels)
 {
     frame->document()->updateStyleAndLayout();
 
     FloatRect pageRect(FloatPoint(0, 0), pageSizeInPixels);
     PrintContext printContext(frame);
     printContext.begin(pageRect.width(), pageRect.height());
     // Account for shrink-to-fit.
     FloatSize scaledPageSize = pageSizeInPixels;
     scaledPageSize.scale(frame->view()->contentsSize().width() / pageRect.width());
     printContext.computePageRectsWithPageSize(scaledPageSize);
     return printContext.pageCount();
 }
 
 DEFINE_TRACE(PrintContext)
 {
     visitor->trace(m_frame);
     visitor->trace(m_linkedDestinations);
 }
 
 } // namespace blink