Add Settings::deviceScaleAdjustment.

Source/core/rendering/TextAutosizer.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2012 Apple Inc. All rights reserved.
  *
  * 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 190 matching lines @@
 
 float TextAutosizer::clusterMultiplier(WritingMode writingMode, const TextAutosizingWindowInfo& windowInfo, float textWidth) const
 {
     int logicalWindowWidth = isHorizontalWritingMode(writingMode) ? windowInfo.windowSize.width() : windowInfo.windowSize.height();
     int logicalLayoutWidth = isHorizontalWritingMode(writingMode) ? windowInfo.minLayoutSize.width() : windowInfo.minLayoutSize.height();
     // Ignore box width in excess of the layout width, to avoid extreme multipliers.
     float logicalClusterWidth = std::min<float>(textWidth, logicalLayoutWidth);
 
     float multiplier = logicalClusterWidth / logicalWindowWidth;
     multiplier *= m_document->settings()->textAutosizingFontScaleFactor();
+
+    // If the page has a meta viewport or @viewport, don't apply the device scale adjustment.
+    const ViewportDescription& viewportDescription = m_document->page()->mainFrame()->document()->viewportDescription();
+    if (!viewportDescription.isSpecifiedByAuthor()) {

[johnme, 2013/11/05 18:56:40]

Didn't we say we'd disable the fontScaleFactor if you have a <= device-width
viewport, or an unscalable viewport? But I didn't think we wanted to disable it
for e.g. a width=1000 viewport.

IIRC the check you want here is the same as I added in
https://codereview.chromium.org/18850005/diff/446001/content/public/android/j...
for disabling double tap zoom, though you'd need to get the values from Blink
not Java :)

[skobes, 2013/11/05 19:02:46]

Actually what we are doing is disabling the 1.05-1.3x multiplier on the font
scale factor for sites with a meta viewport (I believe this is the proposal we
agreed on in our last meeting).  We will still autosize when layout width >
device width.

+        multiplier *= m_document->settings()->deviceScaleAdjustment();
+    }
     return std::max(1.0f, multiplier);
 }
 
 void TextAutosizer::processClusterInternal(TextAutosizingClusterInfo& clusterInfo, RenderBlock* container, RenderObject* subtreeRoot, const TextAutosizingWindowInfo& windowInfo, float multiplier)
 {
     processContainer(multiplier, container, clusterInfo, subtreeRoot, windowInfo);
 
     Vector<Vector<TextAutosizingClusterInfo> > narrowDescendantsGroups;
     getNarrowDescendantsGroupedByWidth(clusterInfo, narrowDescendantsGroups);
     for (size_t i = 0; i < narrowDescendantsGroups.size(); ++i)
@@ skipping 503 matching lines @@
         if (i + 1 < clusterInfos.size()) {
             float currentWidth = clusterInfos[i].root->contentLogicalWidth();
             float nextWidth = clusterInfos[i + 1].root->contentLogicalWidth();
             if (currentWidth - nextWidth > maxWidthDifferenceWithinGroup)
                 groups.grow(groups.size() + 1);
         }
     }
 }
 
 } // namespace WebCore