add HitTestCanvasResult Class instend of std::pair<Element*, String>

third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h

Index: third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h
diff --git a/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h b/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h
index aaf33831899d843bca629adb615a885a1ec6f7f2..71913e2f375645ac8c552bb9ce9fc467318b1eb1 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h
@@ -28,6 +28,7 @@
 
 #include "core/CoreExport.h"
 #include "core/html/HTMLCanvasElement.h"
+#include "core/layout/HitTestCanvasResult.h"
 #include "core/offscreencanvas/OffscreenCanvas.h"
 #include "wtf/HashSet.h"
 #include "wtf/Noncopyable.h"
@@ -107,7 +108,7 @@ public:
     virtual unsigned hitRegionsCount() const { return 0; }
     virtual void setFont(const String&) { }
     virtual void styleDidChange(const ComputedStyle* oldStyle, const ComputedStyle& newStyle) { }
-    virtual std::pair<Element*, String> getControlAndIdIfHitRegionExists(const LayoutPoint& location) { NOTREACHED(); return std::make_pair(nullptr, String()); }
+    virtual HitTestCanvasResult* getControlAndIdIfHitRegionExists(const LayoutPoint& location) { NOTREACHED(); return HitTestCanvasResult::create(String(), nullptr); }
     virtual String getIdFromControl(const Element* element) { return String(); }
     virtual bool isAccelerationOptimalForCanvasContent() const { return true; }
     virtual void resetUsageTracking() { };