Do not increase the pointer id when type is eraser

third_party/WebKit/Source/core/events/PointerEventFactory.cpp

Index: third_party/WebKit/Source/core/events/PointerEventFactory.cpp
diff --git a/third_party/WebKit/Source/core/events/PointerEventFactory.cpp b/third_party/WebKit/Source/core/events/PointerEventFactory.cpp
index 2bbb8654d16dd90a4ce7f35ef1766e82490ffa2c..0e96f0fbfc63ed24f8f20def8ef01cb7350dee33 100644
--- a/third_party/WebKit/Source/core/events/PointerEventFactory.cpp
+++ b/third_party/WebKit/Source/core/events/PointerEventFactory.cpp
@@ -17,20 +17,20 @@ inline int ToInt(WebPointerProperties::PointerType t) {
 
 const char* PointerTypeNameForWebPointPointerType(
     WebPointerProperties::PointerType type) {
+  // TODO(mustaq): Fix when the spec starts supporting hovering erasers.
   switch (type) {
     case WebPointerProperties::PointerType::kUnknown:
       return "";
     case WebPointerProperties::PointerType::kTouch:
       return "touch";
     case WebPointerProperties::PointerType::kPen:
-    case WebPointerProperties::PointerType::kEraser:
-      // TODO(mustaq): Fix when the spec starts supporting hovering erasers.
       return "pen";
     case WebPointerProperties::PointerType::kMouse:
       return "mouse";
+    default:
+      NOTREACHED();
+      return "";
   }
-  NOTREACHED();
-  return "";
 }
 
 const AtomicString& PointerEventNameForMouseEventName(
@@ -188,21 +188,22 @@ void PointerEventFactory::SetIdTypeButtons(
     PointerEventInit& pointer_event_init,
     const WebPointerProperties& pointer_properties,
     unsigned buttons) {
-  const WebPointerProperties::PointerType pointer_type =
+  WebPointerProperties::PointerType pointer_type =
       pointer_properties.pointer_type;
-  const IncomingId incoming_id(pointer_type, pointer_properties.id);
-  int pointer_id = AddIdAndActiveButtons(incoming_id, buttons != 0);
-
   // Tweak the |buttons| to reflect pen eraser mode only if the pen is in
   // active buttons state w/o even considering the eraser button.
   // TODO(mustaq): Fix when the spec starts supporting hovering erasers.
-  if (pointer_type == WebPointerProperties::PointerType::kEraser &&
-      buttons != 0) {
-    buttons |= static_cast<unsigned>(WebPointerProperties::Buttons::kEraser);
-    buttons &= ~static_cast<unsigned>(WebPointerProperties::Buttons::kLeft);
+  if (pointer_type == WebPointerProperties::PointerType::kEraser) {
+    if (buttons != 0) {
+      buttons |= static_cast<unsigned>(WebPointerProperties::Buttons::kEraser);
+      buttons &= ~static_cast<unsigned>(WebPointerProperties::Buttons::kLeft);
+    }
+    pointer_type = WebPointerProperties::PointerType::kPen;
   }
   pointer_event_init.setButtons(buttons);
 
+  const IncomingId incoming_id(pointer_type, pointer_properties.id);
+  int pointer_id = AddIdAndActiveButtons(incoming_id, buttons != 0);
   pointer_event_init.setPointerId(pointer_id);
   pointer_event_init.setPointerType(
       PointerTypeNameForWebPointPointerType(pointer_type));
@@ -515,6 +516,8 @@ bool PointerEventFactory::Remove(const int mapped_id) {
   return true;
 }
 
+// This function does not work with pointer type of eraser, because we save
+// them as pen type in the pointer id map.
 Vector<int> PointerEventFactory::GetPointerIdsOfType(
     WebPointerProperties::PointerType pointer_type) const {
   Vector<int> mapped_ids;