Bug 702948 - Add telemetry to count how many ranges are detached; r=smaug

content/base/src/nsRange.cpp

@@ -62,6 +62,9 @@
 #include "nsLayoutUtils.h"
 #include "nsTextFrame.h"
 #include "nsFontFaceList.h"
+#include "mozilla/Telemetry.h"
+
+using namespace mozilla;
 
 nsresult NS_NewContentIterator(nsIContentIterator** aInstancePtrResult);
 nsresult NS_NewContentSubtreeIterator(nsIContentIterator** aInstancePtrResult);
@@ -243,6 +246,9 @@ nsRange::~nsRange()
 {
   NS_ASSERTION(!IsInSelection(), "deleting nsRange that is in use");
 
+  // Maybe we can remove Detach() -- bug 702948.
+  Telemetry::Accumulate(Telemetry::DOM_RANGE_DETACHED, mIsDetached);
+
   // we want the side effects (releases and list removals)
   DoSetRange(nsnull, 0, nsnull, 0, nsnull);
 } 

toolkit/components/telemetry/TelemetryHistograms.h

@@ -401,6 +401,7 @@ HISTOGRAM_BOOLEAN(MULTIPART_XHR_RESPONSE, "XMLHttpRequest response was of type m
  */
 HISTOGRAM(DOM_TIMERS_FIRED_PER_NATIVE_TIMEOUT, 1, 3000, 10, EXPONENTIAL, "DOM: Timer handlers called per native timer expiration")
 HISTOGRAM(DOM_TIMERS_RECENTLY_SET, 1, 3000, 10, EXPONENTIAL, "DOM: setTimeout/setInterval calls recently (last 30s or more)")
+HISTOGRAM_BOOLEAN(DOM_RANGE_DETACHED, "DOM: Ranges that are detached on destruction (bug 702948)")
 
 /**
  * DOM Storage telemetry.