Move line-specific code into LayoutBlockFlow::positionForPoint().

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

Index: third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
index 97baaabca2d756ceb2d1776496e7c67f0d518d3c..58932b0e1db3c1992a61a5eb95b5df9d767b9e3f 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
@@ -31,6 +31,7 @@
 #include "core/layout/LayoutBlockFlow.h"
 
 #include "core/dom/AXObjectCache.h"
+#include "core/editing/Editor.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
@@ -3180,6 +3181,106 @@ bool LayoutBlockFlow::recalcInlineChildrenOverflowAfterStyleChange()
     return childrenOverflowChanged;
 }
 
+PositionWithAffinity LayoutBlockFlow::positionForPoint(const LayoutPoint& point)
+{
+    if (isAtomicInlineLevel()) {
+        PositionWithAffinity position = positionForPointIfOutsideAtomicInlineLevel(point);
+        if (!position.isNull())
+            return position;
+    }
+    if (!childrenInline())
+        return LayoutBlock::positionForPoint(point);
+
+    LayoutPoint pointInContents = point;
+    offsetForContents(pointInContents);
+    LayoutPoint pointInLogicalContents(pointInContents);
+    if (!isHorizontalWritingMode())
+        pointInLogicalContents = pointInLogicalContents.transposedPoint();
+
+    if (!firstRootBox())
+        return createPositionWithAffinity(0);
+
+    bool linesAreFlipped = style()->isFlippedLinesWritingMode();
+    bool blocksAreFlipped = style()->isFlippedBlocksWritingMode();
+
+    // look for the closest line box in the root box which is at the passed-in y coordinate
+    InlineBox* closestBox = nullptr;
+    RootInlineBox* firstRootBoxWithChildren = nullptr;
+    RootInlineBox* lastRootBoxWithChildren = nullptr;
+    for (RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox()) {
+        if (!root->firstLeafChild())
+            continue;
+        if (!firstRootBoxWithChildren)
+            firstRootBoxWithChildren = root;
+
+        if (!linesAreFlipped && root->isFirstAfterPageBreak() && (pointInLogicalContents.y() < root->lineTopWithLeading()
+            || (blocksAreFlipped && pointInLogicalContents.y() == root->lineTopWithLeading())))
+            break;
+
+        lastRootBoxWithChildren = root;
+
+        // check if this root line box is located at this y coordinate
+        if (pointInLogicalContents.y() < root->selectionBottom() || (blocksAreFlipped && pointInLogicalContents.y() == root->selectionBottom())) {
+            if (linesAreFlipped) {
+                RootInlineBox* nextRootBoxWithChildren = root->nextRootBox();
+                while (nextRootBoxWithChildren && !nextRootBoxWithChildren->firstLeafChild())
+                    nextRootBoxWithChildren = nextRootBoxWithChildren->nextRootBox();
+
+                if (nextRootBoxWithChildren && nextRootBoxWithChildren->isFirstAfterPageBreak() && (pointInLogicalContents.y() > nextRootBoxWithChildren->lineTopWithLeading()
+                    || (!blocksAreFlipped && pointInLogicalContents.y() == nextRootBoxWithChildren->lineTopWithLeading())))
+                    continue;
+            }
+            closestBox = root->closestLeafChildForLogicalLeftPosition(pointInLogicalContents.x());
+            if (closestBox)
+                break;
+        }
+    }
+
+    bool moveCaretToBoundary = document().frame()->editor().behavior().shouldMoveCaretToHorizontalBoundaryWhenPastTopOrBottom();
+
+    if (!moveCaretToBoundary && !closestBox && lastRootBoxWithChildren) {
+        // y coordinate is below last root line box, pretend we hit it
+        closestBox = lastRootBoxWithChildren->closestLeafChildForLogicalLeftPosition(pointInLogicalContents.x());
+    }
+
+    if (closestBox) {
+        if (moveCaretToBoundary) {
+            LayoutUnit firstRootBoxWithChildrenTop = std::min<LayoutUnit>(firstRootBoxWithChildren->selectionTop(), firstRootBoxWithChildren->logicalTop());
+            if (pointInLogicalContents.y() < firstRootBoxWithChildrenTop
+                || (blocksAreFlipped && pointInLogicalContents.y() == firstRootBoxWithChildrenTop)) {
+                InlineBox* box = firstRootBoxWithChildren->firstLeafChild();
+                if (box->isLineBreak()) {
+                    if (InlineBox* newBox = box->nextLeafChildIgnoringLineBreak())
+                        box = newBox;
+                }
+                // y coordinate is above first root line box, so return the start of the first
+                return PositionWithAffinity(positionForBox(box, true));
+            }
+        }
+
+        // pass the box a top position that is inside it
+        LayoutPoint point(pointInLogicalContents.x(), closestBox->root().blockDirectionPointInLine());
+        if (!isHorizontalWritingMode())
+            point = point.transposedPoint();
+        if (closestBox->getLineLayoutItem().isAtomicInlineLevel())
+            return positionForPointRespectingEditingBoundaries(LineLayoutBox(closestBox->getLineLayoutItem()), point);
+        return closestBox->getLineLayoutItem().positionForPoint(point);
+    }
+
+    if (lastRootBoxWithChildren) {
+        // We hit this case for Mac behavior when the Y coordinate is below the last box.
+        ASSERT(moveCaretToBoundary);
+        InlineBox* logicallyLastBox;
+        if (lastRootBoxWithChildren->getLogicalEndBoxWithNode(logicallyLastBox))
+            return PositionWithAffinity(positionForBox(logicallyLastBox, false));
+    }
+
+    // Can't reach this. We have a root line box, but it has no kids.
+    // FIXME: This should ASSERT_NOT_REACHED(), but clicking on placeholder text
+    // seems to hit this code path.
+    return createPositionWithAffinity(0);
+}
+
 #ifndef NDEBUG
 
 void LayoutBlockFlow::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const LayoutObject* obj) const