Disable FTA when max multiplier is 1.

Source/core/rendering/FastTextAutosizer.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 49 matching lines @@
     {
         return adoptPtr(new FastTextAutosizer(document));
     }
 
     void record(const RenderBlock*);
     void destroy(const RenderBlock*);
     void inflateListItem(RenderListItem*, RenderListMarker*);
 
     class LayoutScope {
     public:
-        explicit LayoutScope(Document& document, RenderBlock* block)
-            : m_block(0)
-        {
-            m_textAutosizer = document.fastTextAutosizer();
-            if (m_textAutosizer) {
-                if (!m_textAutosizer->enabled()) {
-                    m_textAutosizer = 0;
-                    return;
-                }
-                m_block = block;
-                m_textAutosizer->beginLayout(m_block);
-            }
-        }
-
-        ~LayoutScope()
-        {
-            if (m_textAutosizer)
-                m_textAutosizer->endLayout(m_block);
-        }
+        explicit LayoutScope(RenderBlock*);
+        ~LayoutScope();
     private:
         FastTextAutosizer* m_textAutosizer;
         RenderBlock* m_block;
     };
 
 private:
     typedef HashSet<const RenderBlock*> BlockSet;
 
     enum HasEnoughTextToAutosize {
         Unknown,
@@ skipping 91 matching lines @@
         ReverseFingerprintMap m_blocksForFingerprint;
     };
 
     explicit FastTextAutosizer(const Document*);
 
     void beginLayout(RenderBlock*);
     void endLayout(RenderBlock*);
     void inflateTable(RenderTable*);
     void inflate(RenderBlock*);
     bool enabled();
-    void prepareRenderViewInfo();
+    void updateRenderViewInfo();
     void prepareClusterStack(const RenderObject*);
     bool isFingerprintingCandidate(const RenderBlock*);
     bool clusterHasEnoughTextToAutosize(Cluster*, const RenderBlock* widthProvider = 0);
     bool clusterWouldHaveEnoughTextToAutosize(const RenderBlock* root, const RenderBlock* widthProvider = 0);
     Fingerprint getFingerprint(const RenderObject*);
     Fingerprint computeFingerprint(const RenderObject*);
     Cluster* maybeCreateCluster(const RenderBlock*);
     Supercluster* getSupercluster(const RenderBlock*);
     const RenderBlock* deepestCommonAncestor(BlockSet&);
     float clusterMultiplier(Cluster*);
     float superclusterMultiplier(Supercluster*);
     // A cluster's width provider is typically the deepest block containing all text.
     // There are exceptions, such as tables and table cells which use the table itself for width.
     const RenderBlock* clusterWidthProvider(const RenderBlock*);
     // Typically this returns a block's computed width. In the case of tables layout, this
     // width is not yet known so the fixed width is used if it's available, or the containing
     // block's width otherwise.
     float widthFromBlock(const RenderBlock*);
     float multiplierFromBlock(const RenderBlock*);
     void applyMultiplier(RenderObject*, float);
     bool mightBeWiderOrNarrowerDescendant(const RenderBlock*);
     bool isWiderOrNarrowerDescendant(Cluster*);
     bool isLayoutRoot(const RenderBlock*) const;
+    bool isInLayout() const;
 
     Cluster* currentCluster() const;
 
     RenderObject* nextChildSkippingChildrenOfBlocks(const RenderObject*, const RenderObject*);
 
     const RenderBlock* deepestBlockContainingAllText(Cluster*);
     const RenderBlock* deepestBlockContainingAllText(const RenderBlock*);
     // Returns the first text leaf that is in the current cluster. We attempt to not include text
     // from descendant clusters but because descendant clusters may not exist, this is only an approximation.
     // The TraversalDirection controls whether we return the first or the last text leaf.
     const RenderObject* findTextLeaf(const RenderObject*, size_t&, TextLeafSearch);
 
     const Document* m_document;
     int m_frameWidth; // LocalFrame width in density-independent pixels (DIPs).
     int m_layoutWidth; // Layout width in CSS pixels.
     float m_baseMultiplier; // Includes accessibility font scale factor and device scale adjustment.
+    float m_maxMultiplier; // Maximum possible multiplier for the current base multiplier and layout/frame width.
     const RenderBlock* m_firstBlock; // First block to receive beginLayout.
 #ifndef NDEBUG
     bool m_renderViewInfoPrepared;
     BlockSet m_blocksThatHaveBegunLayout; // Used to ensure we don't compute properties of a block before beginLayout() is called on it.
 #endif
 
     // Clusters are created and destroyed during layout. The map key is the
     // cluster root. Clusters whose roots share the same fingerprint use the
     // same multiplier.
     SuperclusterMap m_superclusters;
     ClusterStack m_clusterStack;
     FingerprintMapper m_fingerprintMapper;
 };
 
 } // namespace WebCore
 
 #endif // FastTextAutosizer_h