Reconstrain zoom value to the [min-zoom, max-zoom] range before it used

third_party/WebKit/Source/core/dom/ViewportDescription.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 183 matching lines @@
 
   // 8. Resolve height value.
   if (resultHeight == ViewportDescription::ValueAuto) {
     if (!initialViewportSize.width())
       resultHeight = initialViewportSize.height();
     else
       resultHeight = resultWidth * initialViewportSize.height() /
                      initialViewportSize.width();
   }
 
-  // Resolve initial-scale value.
+  // 9. Resolve initial-scale value.

[rune, 2016/10/31 14:45:03]

The numbering used to correspond with the numbering in the spec. This probably
broke when Florian rewrote the spec to use Bikeshed. There's no point in putting
9 here, at least.

This block is implementing
https://www.w3.org/TR/css-device-adapt-1/#handling-auto-zoom

That section already says the resulting viewport based zoom should be
constrained by the min/max values.

[bokan, 2016/10/31 14:47:55]

In that case, since the numbers no longer correspond to anything, please remove
the numbers on all the comments.

   if (resultZoom == ViewportDescription::ValueAuto) {
     if (resultWidth != ViewportDescription::ValueAuto && resultWidth > 0)
       resultZoom = initialViewportSize.width() / resultWidth;
     if (resultHeight != ViewportDescription::ValueAuto && resultHeight > 0) {
       // if 'auto', the initial-scale will be negative here and thus ignored.
       resultZoom = std::max<float>(resultZoom,
                                    initialViewportSize.height() / resultHeight);
     }
   }
 
+  // 10. Reconstrain zoom value to the [min-zoom, max-zoom] range. It will reset
+  // below, if it is ValueAuto.
+  resultZoom = compareIgnoringAuto(
+      resultMinZoom, compareIgnoringAuto(resultMaxZoom, resultZoom, std::min),
+      std::max);

[rune, 2016/10/31 14:45:03]

This can be moved inside the block above, right?

+
   // If user-scalable = no, lock the min/max scale to the computed initial
   // scale.
   if (!resultUserZoom)
     resultMinZoom = resultMaxZoom = resultZoom;
 
   // Only set initialScale to a value if it was explicitly set.
   if (zoom == ViewportDescription::ValueAuto)
     resultZoom = ViewportDescription::ValueAuto;
 
   PageScaleConstraints result;
@@ skipping 67 matching lines @@
     metaTagTypeHistogram.count(MobileOptimizedMeta);
   }
 #endif
 }
 
 bool ViewportDescription::matchesHeuristicsForGpuRasterization() const {
   return isSpecifiedByAuthor();
 }
 
 }  // namespace blink