[Android WebView] Treat zero values in viewport arguments specially

Source/core/dom/ViewportArguments.h

 /*
  * 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 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)
  * Copyright (C) 2012-2013 Intel Corporation. All rights reserved.
  *
@@ skipping 36 matching lines @@
 
 struct ViewportArguments {
 
     enum Type {
         // These are ordered in increasing importance.
         Implicit,
         XHTMLMobileProfile,
         HandheldFriendlyMeta,
         MobileOptimizedMeta,
         ViewportMeta,
-        ViewportMetaLayoutSizeQuirk,
+        ViewportMetaLayoutSizeAndZeroValuesQuirk,

[rune, 2013/09/02 06:25:14]

Is it important that these quirks can be turned on/off and change effect during
the lifetime of a WebView?

If not, I think I would have done the quirks during viewport meta tag
processing, and not as part of ViewportArguments::resolve. That will make
ViewportArguments::resolve less cluttery and make it possible to remove these
modes completely.

I see now that it's not possible to skip the extend-width part like that with
the current code, but still I'd like to know if changing that setting needs to
have an effect on a document that is already loaded in that WebView. Just to
know how we can rewrite this quirk for the new code.

[kenneth.r.christiansen, 2013/09/02 06:45:04]

I would also really like to have these be runtime settings instead of tied into
the ViewportArguments as a specialized type

[mnaganov (inactive), 2013/09/02 13:25:53]

No. We can assume that they are constant during the lifetime of a WebView.
Not everything can be easily done during the processing stage, as sometimes
decisions depend on the values of other fields of the tag. While during the
processing stage the fields are considered independently. But thanks to your
proposal, I have found that at least it is possible to separate those two
quirks.
 

         CSSDeviceAdaptation
     } type;
 
     enum {
         ValueAuto = -1,
         ValueDeviceWidth = -2,
         ValueDeviceHeight = -3,
         ValuePortrait = -4,
         ValueLandscape = -5,
         ValueDeviceDPI = -6,
@@ skipping 59 matching lines @@
         return !(*this == other);
     }
 };
 
 void setViewportFeature(const String& keyString, const String& valueString, Document*, void* data);
 void reportViewportWarning(Document*, ViewportErrorCode, const String& replacement1, const String& replacement2);
 
 } // namespace WebCore
 
 #endif // ViewportArguments_h