Canvas2d: Implement rerouting event by hit region's control.

third_party/WebKit/Source/core/input/EventHandler.h

Index: third_party/WebKit/Source/core/input/EventHandler.h
diff --git a/third_party/WebKit/Source/core/input/EventHandler.h b/third_party/WebKit/Source/core/input/EventHandler.h
index d29d956d7f26d35f95e06cd26356f7baf826a9f6..5a141ccf8fcc9b90506fa97bb429e2ae4640e2b4 100644
--- a/third_party/WebKit/Source/core/input/EventHandler.h
+++ b/third_party/WebKit/Source/core/input/EventHandler.h
@@ -225,6 +225,7 @@ public:
         FloatSize adjustedRadius;
         bool knownTarget;
         bool consumed;
+        String region;
     };
 
 private:
@@ -429,6 +430,8 @@ private:
     // The target of each active touch point indexed by the touch ID.
     using TouchTargetMap = WillBeHeapHashMap<unsigned, RefPtrWillBeMember<EventTarget>, DefaultHash<unsigned>::Hash, WTF::UnsignedWithZeroKeyHashTraits<unsigned>>;
     TouchTargetMap m_targetForTouchID;
+    using TouchRegionMap = WillBeHeapHashMap<unsigned, String, DefaultHash<unsigned>::Hash, WTF::UnsignedWithZeroKeyHashTraits<unsigned>>;
+    TouchRegionMap m_regionForTouchID;
 
     // If set, the document of the active touch sequence. Unset if no touch sequence active.
     RefPtrWillBeMember<Document> m_touchSequenceDocument;