Update histogram's names for ChromeArcVideoDecodeAccelerator.

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 94024562c2ec8501b5c5aac4e601e6a04c2ab678..3571ad8fff8a39f9f3d538329db4a0fabfe24d1c 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -27170,7 +27170,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Media.ArcGpuVideoDecodeAccelerator.InitializeResult"
-    enum="ArcVideoAcceleratorResult">
+    enum="ArcVideoAcceleratorResultObsolete">
+  <obsolete>
+    Deprecated as of June 12, 2017. Replaced by
+    Media.ChromeArcVideoDecodeAccelerator.InitializeResult.
+  </obsolete>
   <owner>johnylin@chromium.org</owner>
   <summary>
     Counts of status values returned from calls to
@@ -28003,6 +28007,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Media.ChromeArcVideoDecodeAccelerator.InitializeResult"
+    enum="ArcVideoDecodeAcceleratorResult">
+  <owner>johnylin@chromium.org</owner>
+  <summary>
+    Counts of status values returned from calls to
+    ChromeArcVideoDecodeAccelerator::Initialize().
+  </summary>
+</histogram>
+
 <histogram name="Media.ChromeCast.DelayedAndDroppedFramesPer5Sec"
     units="frames/5s">
   <owner>mfoltz@chromium.org</owner>