Add UseCounters for Selection methods that take null

third_party/WebKit/Source/core/editing/DOMSelection.cpp

Index: third_party/WebKit/Source/core/editing/DOMSelection.cpp
diff --git a/third_party/WebKit/Source/core/editing/DOMSelection.cpp b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
index d1d378ff0f4071771e4965932dcb043b64f536bd..cad8eb8070a17426922713cc286c5a08dd1d14e9 100644
--- a/third_party/WebKit/Source/core/editing/DOMSelection.cpp
+++ b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
@@ -43,6 +43,7 @@
 #include "core/editing/FrameSelection.h"
 #include "core/editing/iterators/TextIterator.h"
 #include "core/frame/LocalFrame.h"
+#include "core/frame/UseCounter.h"
 #include "core/inspector/ConsoleMessage.h"
 #include "wtf/text/WTFString.h"
 
@@ -208,6 +209,7 @@ void DOMSelection::collapse(Node* node, int offset, ExceptionState& exceptionSta
         return;
 
     if (!node) {
+        UseCounter::count(m_frame, UseCounter::SelectionCollapseNull);
         m_frame->selection().clear();
         return;
     }
@@ -281,6 +283,9 @@ void DOMSelection::setBaseAndExtent(Node* baseNode, int baseOffset, Node* extent
         return;
     }
 
+    if (!baseNode || !extentNode)
+        UseCounter::count(m_frame, UseCounter::SelectionSetBaseAndExtentNull);
+
     if (!isValidForPosition(baseNode) || !isValidForPosition(extentNode))
         return;