Detect HDR capability

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 2066ab170e99b48ffbc46b490a0439b07c9b7ca5..4e6556d20403a6c4ae968a3ca9884090f23c610e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -23550,6 +23550,33 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="GPU.Output.ColorSpace" enum="DXGI_COLOR_SPACE_TYPE">
+  <owner>hubbe@chromium.org</owner>
+  <owner>media-dev@chromium.org</owner>
+  <summary>
+    Records the output color space of the monitor as reported by windows.

[Mark P, 2017/06/26 21:30:59]

nit: windows -> Windows
ditto bottom histogram.

[hubbe, 2017/06/26 22:08:59]

Done.

+    Recorded once for each monitor when the gpu process starts.
+  </summary>
+</histogram>
+
+<histogram name="GPU.Output.HDR" enum="Boolean">
+  <owner>hubbe@chromium.org</owner>
+  <owner>media-dev@chromium.org</owner>
+  <summary>
+    Records if the output monitor is HDR capable. Recorded when the gpu process
+    starts.

[Mark P, 2017/06/26 21:30:59]

Please revise.  "the output monitor".  There may be more than one.

Also, perhaps add: "Only recorded on Windows as of M-61." or something, to make
it clear that it's reasonable at least for now to compare the counts and values
of this to the other GPU histograms you're adding.

[hubbe, 2017/06/26 22:08:59]

Done.

+  </summary>
+</histogram>
+
+<histogram name="GPU.Output.MaxLuminance" units="lumens">
+  <owner>hubbe@chromium.org</owner>
+  <owner>media-dev@chromium.org</owner>
+  <summary>
+    Records the display maximum lumens as reported by windows.
+    Recorded once for each monitor when the gpu process starts.
+  </summary>
+</histogram>
+
 <histogram name="GPU.ProgramCache.BinaryCacheHitTime" units="microseconds">
   <owner>vmiura@chromium.org</owner>
   <summary>The time to load a gpu program from the program cache.</summary>