Send an empty tooltip text when hovering over a different node

third_party/WebKit/Source/core/page/ChromeClient.cpp

Index: third_party/WebKit/Source/core/page/ChromeClient.cpp
diff --git a/third_party/WebKit/Source/core/page/ChromeClient.cpp b/third_party/WebKit/Source/core/page/ChromeClient.cpp
index 05238fe1cbbfb262c462aad2cbaf99cee8da6f50..34782641ad47786a8d7fa548ca16eb33ebc3cc19 100644
--- a/third_party/WebKit/Source/core/page/ChromeClient.cpp
+++ b/third_party/WebKit/Source/core/page/ChromeClient.cpp
@@ -38,6 +38,11 @@
 
 namespace blink {
 
+DEFINE_TRACE(ChromeClient) {
+  visitor->trace(m_lastMouseOverNode);
+  HostWindow::trace(visitor);
+}
+
 void ChromeClient::setWindowRectWithAdjustment(const IntRect& pendingRect,
                                                LocalFrame& frame) {
   IntRect screen = screenInfo().availableRect;
@@ -188,8 +193,18 @@ void ChromeClient::setToolTip(LocalFrame& frame, const HitTestResult& result) {
   if (m_lastToolTipPoint == result.hitTestLocation().point() &&
       m_lastToolTipText == toolTip)
     return;
+
+  // If a tooltip was displayed earlier, and the user has moved the mouse
+  // cursor over a different node, make sure the previous tooltip is unset.
+  // If the newly hovered node has a tooltip, then ::setToolTip will be called
+  // later with the new text.
+  if (result.innerNodeOrImageMapImage() != m_lastMouseOverNode &&
+      !m_lastToolTipText.isEmpty() && toolTip == m_lastToolTipText)
+    clearToolTip(frame);
+
   m_lastToolTipPoint = result.hitTestLocation().point();
   m_lastToolTipText = toolTip;
+  m_lastMouseOverNode = result.innerNodeOrImageMapImage();
   setToolTip(frame, toolTip, toolTipDirection);
 }