Remove Render.Workers.MaxWorkerCountInRendererProcess UMA.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 456e5f4a83e30f559265773946e25da076915bbf..a0185e9eaf5f4842178f06eec7d435c1db138d2c 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -51647,6 +51647,13 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Render.Workers.MaxWorkerCountInRendererProcess">
+  <obsolete>
+    Deprecated Dec 2016. This metric did not report the number of shared workers
+    correctly, since it used the RenderProcessHostImpl ref counts, which in the
+    shared worker case is more like a boolean flag (zero or one or maybe two)
+    than the number of shared workers. So its results can be thought of as
+    roughly the number of service workers only.
+  </obsolete>
   <owner>kinuko@chromium.org</owner>
   <summary>
     Maximum number of workers (SharedWorker or ServiceWorker) that are