(reland) Do not let text-size-adjust override accessibility font settings

third_party/WebKit/Source/core/layout/TextAutosizer.cpp

Index: third_party/WebKit/Source/core/layout/TextAutosizer.cpp
diff --git a/third_party/WebKit/Source/core/layout/TextAutosizer.cpp b/third_party/WebKit/Source/core/layout/TextAutosizer.cpp
index 5fa4132aebff94f1c0cfece478a5b10fd8520d44..26fa19a1f3373c13b895c425c3f762a3c1507686 100644
--- a/third_party/WebKit/Source/core/layout/TextAutosizer.cpp
+++ b/third_party/WebKit/Source/core/layout/TextAutosizer.cpp
@@ -109,8 +109,8 @@ void TextAutosizer::writeClusterDebugInfo(Cluster* cluster)
     }
     String pageInfo = "";
     if (cluster->m_root->isLayoutView()) {
-        pageInfo = String::format("; pageinfo: bm %f * (lw %d / fw %d)",
-            m_pageInfo.m_baseMultiplier, m_pageInfo.m_layoutWidth, m_pageInfo.m_frameWidth);
+        pageInfo = String::format("; pageinfo: afsf %f * dsa %f * (lw %d / fw %d)",
+            m_pageInfo.m_accessibilityFontScaleFactor, m_pageInfo.m_deviceScaleAdjustment, m_pageInfo.m_layoutWidth, m_pageInfo.m_frameWidth);
     }
     float multiplier = cluster->m_flags & SUPPRESSING ? 1.0 : cluster->m_multiplier;
     writeDebugInfo(const_cast<LayoutBlock*>(cluster->m_root),
@@ -552,24 +552,27 @@ void TextAutosizer::updatePageInfo()
         IntSize layoutSize = mainFrame->view()->layoutSize();
         m_pageInfo.m_layoutWidth = horizontalWritingMode ? layoutSize.width() : layoutSize.height();
 
-        // Compute the base font scale multiplier based on device and accessibility settings.
-        m_pageInfo.m_baseMultiplier = m_document->settings()->accessibilityFontScaleFactor();
+        // TODO(pdr): Accessibility should be moved out of the text autosizer. See: crbug.com/645717.
+        m_pageInfo.m_accessibilityFontScaleFactor = m_document->settings()->accessibilityFontScaleFactor();
+
         // If the page has a meta viewport or @viewport, don't apply the device scale adjustment.
-        const ViewportDescription& viewportDescription = mainFrame->document()->viewportDescription();
-        if (!viewportDescription.isSpecifiedByAuthor()) {
-            float deviceScaleAdjustment = m_document->settings()->deviceScaleAdjustment();
-            m_pageInfo.m_baseMultiplier *= deviceScaleAdjustment;
-        }
+        if (!mainFrame->document()->viewportDescription().isSpecifiedByAuthor())
+            m_pageInfo.m_deviceScaleAdjustment = m_document->settings()->deviceScaleAdjustment();
+        else
+            m_pageInfo.m_deviceScaleAdjustment = 1.0f;
 
+        // TODO(pdr): pageNeedsAutosizing should take into account whether text-size-adjust is used
+        // anywhere on the page because that also needs to trigger autosizing. See: crbug.com/646237.
         m_pageInfo.m_pageNeedsAutosizing = !!m_pageInfo.m_frameWidth
-            && (m_pageInfo.m_baseMultiplier * (static_cast<float>(m_pageInfo.m_layoutWidth) / m_pageInfo.m_frameWidth) > 1.0f);
+            && (m_pageInfo.m_accessibilityFontScaleFactor * m_pageInfo.m_deviceScaleAdjustment * (static_cast<float>(m_pageInfo.m_layoutWidth) / m_pageInfo.m_frameWidth) > 1.0f);
     }
 
     if (m_pageInfo.m_pageNeedsAutosizing) {
         // If page info has changed, multipliers may have changed. Force a layout to recompute them.
         if (m_pageInfo.m_frameWidth != previousPageInfo.m_frameWidth
             || m_pageInfo.m_layoutWidth != previousPageInfo.m_layoutWidth
-            || m_pageInfo.m_baseMultiplier != previousPageInfo.m_baseMultiplier
+            || m_pageInfo.m_accessibilityFontScaleFactor != previousPageInfo.m_accessibilityFontScaleFactor
+            || m_pageInfo.m_deviceScaleAdjustment != previousPageInfo.m_deviceScaleAdjustment
             || m_pageInfo.m_settingEnabled != previousPageInfo.m_settingEnabled)
             setAllTextNeedsLayout();
     } else if (previousPageInfo.m_hasAutosized) {
@@ -901,9 +904,10 @@ float TextAutosizer::multiplierFromBlock(const LayoutBlock* block)
 
     // Block width, in CSS pixels.
     float blockWidth = widthFromBlock(block);
-    float multiplier = m_pageInfo.m_frameWidth ? std::min(blockWidth, static_cast<float>(m_pageInfo.m_layoutWidth)) / m_pageInfo.m_frameWidth : 1.0f;
-
-    return std::max(m_pageInfo.m_baseMultiplier * multiplier, 1.0f);
+    float layoutWidth = std::min(blockWidth, static_cast<float>(m_pageInfo.m_layoutWidth));
+    float multiplier = m_pageInfo.m_frameWidth ? layoutWidth / m_pageInfo.m_frameWidth : 1.0f;
+    multiplier *= m_pageInfo.m_accessibilityFontScaleFactor * m_pageInfo.m_deviceScaleAdjustment;
+    return std::max(multiplier, 1.0f);
 }
 
 const LayoutBlock* TextAutosizer::deepestBlockContainingAllText(Cluster* cluster)
@@ -988,10 +992,10 @@ void TextAutosizer::applyMultiplier(LayoutObject* layoutObject, float multiplier
 {
     ASSERT(layoutObject);
     ComputedStyle& currentStyle = layoutObject->mutableStyleRef();
-    // TODO(pdr): text-size-adjust is temporarily not honored due to
-    // breaking accessibility settings. See: https://645269.
-    if (false && !currentStyle.getTextSizeAdjust().isAuto()) {
-        multiplier = currentStyle.getTextSizeAdjust().multiplier();
+    if (!currentStyle.getTextSizeAdjust().isAuto()) {
+        // The accessibility font scale factor is applied by the autosizer so we need to apply that
+        // scale factor on top of the text-size-adjust multiplier.
+        multiplier = currentStyle.getTextSizeAdjust().multiplier() * m_pageInfo.m_accessibilityFontScaleFactor;
     } else if (multiplier < 1) {
         // Unlike text-size-adjust, the text autosizer should only inflate fonts.
         multiplier = 1;