Delay instantiating InputDeviceCapabilities until accessed.

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

Index: third_party/WebKit/Source/core/events/UIEvent.cpp
diff --git a/third_party/WebKit/Source/core/events/UIEvent.cpp b/third_party/WebKit/Source/core/events/UIEvent.cpp
index 178350dcd0cb6648df2bf8dad392d005c2a83dda..0a76237b6dfdb818eff1543abcd2148a2c214053 100644
--- a/third_party/WebKit/Source/core/events/UIEvent.cpp
+++ b/third_party/WebKit/Source/core/events/UIEvent.cpp
@@ -22,8 +22,6 @@
 
 #include "core/events/UIEvent.h"
 
-#include "core/input/InputDeviceCapabilities.h"
-
 namespace blink {
 
 UIEvent::UIEvent() : m_detail(0), m_sourceCapabilities(nullptr) {}
@@ -35,7 +33,7 @@ UIEvent::UIEvent(const AtomicString& eventType,
                  TimeTicks platformTimeStamp,
                  AbstractView* viewArg,
                  int detailArg,
-                 InputDeviceCapabilities* sourceCapabilitiesArg)
+                 const InputDeviceCapabilitiesValue& sourceCapabilitiesArg)
     : Event(eventType,
             canBubbleArg,
             cancelableArg,
@@ -59,7 +57,7 @@ void UIEvent::initUIEvent(const AtomicString& typeArg,
                           AbstractView* viewArg,
                           int detailArg) {
   initUIEventInternal(typeArg, canBubbleArg, cancelableArg, nullptr, viewArg,
-                      detailArg, nullptr);
+                      detailArg, InputDeviceCapabilities::Null);
 }
 
 void UIEvent::initUIEventInternal(
@@ -69,7 +67,7 @@ void UIEvent::initUIEventInternal(
     EventTarget* relatedTarget,
     AbstractView* viewArg,
     int detailArg,
-    InputDeviceCapabilities* sourceCapabilitiesArg) {
+    const InputDeviceCapabilitiesValue& sourceCapabilitiesArg) {
   if (isBeingDispatched())
     return;
 
@@ -92,6 +90,13 @@ int UIEvent::which() const {
   return 0;
 }
 
+InputDeviceCapabilities* UIEvent::sourceCapabilities() {
+  // TODO: align with what the spec decides for the scope of
+  // |sourceCapabilities|. i.e., the returned instance may end up as being
+  // unique per-UIEvent, not window.
+  return m_sourceCapabilities.getCapabilities(m_view);
+}
+
 DEFINE_TRACE(UIEvent) {
   visitor->trace(m_view);
   visitor->trace(m_sourceCapabilities);