Expand tap highlight to allow multiple highlights for touch disambiguation.

Source/core/platform/graphics/GraphicsLayer.cpp

Index: Source/core/platform/graphics/GraphicsLayer.cpp
diff --git a/Source/core/platform/graphics/GraphicsLayer.cpp b/Source/core/platform/graphics/GraphicsLayer.cpp
index 461c2547c35e2854a9e7975e4a4a4fab0de097d9..5f80db3e44f940a183e6c5d5d024af1e897a6111 100644
--- a/Source/core/platform/graphics/GraphicsLayer.cpp
+++ b/Source/core/platform/graphics/GraphicsLayer.cpp
@@ -131,7 +131,6 @@ GraphicsLayer::GraphicsLayer(GraphicsLayerClient* client)
     , m_repaintCount(0)
     , m_contentsLayer(0)
     , m_contentsLayerId(0)
-    , m_linkHighlight(0)
     , m_contentsLayerPurpose(NoContentsLayer)
     , m_scrollableArea(0)
 {
@@ -149,10 +148,9 @@ GraphicsLayer::GraphicsLayer(GraphicsLayerClient* client)
 
 GraphicsLayer::~GraphicsLayer()
 {
-    if (m_linkHighlight) {
-        m_linkHighlight->clearCurrentGraphicsLayer();
-        m_linkHighlight = 0;
-    }
+    for (size_t i = 0; i < m_linkHighlights.size(); i++)
+        m_linkHighlights[i]->clearCurrentGraphicsLayer();
+    m_linkHighlights.clear();
 
 #ifndef NDEBUG
     if (m_client)
@@ -564,9 +562,9 @@ void GraphicsLayer::updateNames()
         String debugName = "ContentsLayer for " + m_nameBase;
         contentsLayer->setDebugName(debugName);
     }
-    if (m_linkHighlight) {
+    for (size_t i = 0; i < m_linkHighlights.size(); i++) {
         String debugName = "LinkHighlight for " + m_nameBase;
-        m_linkHighlight->layer()->setDebugName(debugName);
+        m_linkHighlights[i]->layer()->setDebugName(debugName);

[wjmaclean, 2013/06/12 15:09:06]

It may be slightly confusing having multiple link highlight layers all with the
same name ... can they at least be numbered or something to indicate that it's
ok for there to be more than one?

     }
 }
 
@@ -592,8 +590,8 @@ void GraphicsLayer::updateChildList()
         childHost->addChild(curChild->platformLayer());
     }
 
-    if (m_linkHighlight)
-        childHost->addChild(m_linkHighlight->layer());
+    for (size_t i = 0; i < m_linkHighlights.size(); i++)
+        childHost->addChild(m_linkHighlights[i]->layer());
 }
 
 void GraphicsLayer::updateLayerIsDrawable()
@@ -609,8 +607,8 @@ void GraphicsLayer::updateLayerIsDrawable()
 
     if (m_drawsContent) {
         m_layer->layer()->invalidate();
-        if (m_linkHighlight)
-            m_linkHighlight->invalidate();
+        for (size_t i = 0; i < m_linkHighlights.size(); i++)
+            m_linkHighlights[i]->invalidate();
     }
 }
 
@@ -942,7 +940,9 @@ void GraphicsLayer::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
     info.addMember(m_layer, "layer");
     info.addMember(m_imageLayer, "imageLayer");
     info.addMember(m_contentsLayer, "contentsLayer");
-    info.addMember(m_linkHighlight, "linkHighlight");
+    for (size_t i = 0; i < m_linkHighlights.size(); i++) {
+        info.addMember(m_linkHighlights[i], "linkHighlights");
+    }
     info.addMember(m_opaqueRectTrackingContentLayerDelegate, "opaqueRectTrackingContentLayerDelegate");
     info.addMember(m_animationIdMap, "animationIdMap");
     info.addMember(m_scrollableArea, "scrollableArea");
@@ -1098,8 +1098,8 @@ void GraphicsLayer::setNeedsDisplay()
     if (drawsContent()) {
         m_layer->layer()->invalidate();
         addRepaintRect(FloatRect(FloatPoint(), m_size));
-        if (m_linkHighlight)
-            m_linkHighlight->invalidate();
+        for (size_t i = 0; i < m_linkHighlights.size(); i++)
+            m_linkHighlights[i]->invalidate();
     }
 }
 
@@ -1108,8 +1108,8 @@ void GraphicsLayer::setNeedsDisplayInRect(const FloatRect& rect)
     if (drawsContent()) {
         m_layer->layer()->invalidateRect(rect);
         addRepaintRect(rect);
-        if (m_linkHighlight)
-            m_linkHighlight->invalidate();
+        for (size_t i = 0; i < m_linkHighlights.size(); i++)
+            m_linkHighlights[i]->invalidate();
     }
 }
 
@@ -1331,9 +1331,18 @@ void GraphicsLayer::setBackgroundFilters(const FilterOperations& filters)
     m_layer->layer()->setBackgroundFilters(webFilters);
 }
 
-void GraphicsLayer::setLinkHighlight(LinkHighlightClient* linkHighlight)
+void GraphicsLayer::addLinkHighlight(LinkHighlightClient* linkHighlight)
+{
+    ASSERT(linkHighlight);
+    m_linkHighlights.append(linkHighlight);
+    updateChildList();
+}
+
+void GraphicsLayer::removeLinkHighlight(
+    LinkHighlightClient* linkHighlight)
 {
-    m_linkHighlight = linkHighlight;
+    m_linkHighlights.remove(m_linkHighlights.find(linkHighlight));
+    ASSERT(!m_linkHighlights.contains(linkHighlight));
     updateChildList();
 }