Add VaapiVideoEncodeAccelerator for HW-accelerated video encode.

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 fb3d9a74f13a3458e4bd0a0f92d83d117d1e7896..5e30a1a2f8c15255b4876b6f2393bd3e58235b88 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -10214,6 +10214,13 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Media.VAVEA.EncoderFailure" enum="VAVEAEncoderFailure">
+  <owner>posciak@chromium.org</owner>
+  <summary>
+    Error codes reported by video encode using VA-API hardware video encoder.
+  </summary>
+</histogram>
+
 <histogram name="Media.VideoCapture.AspectRatio">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>
@@ -45443,6 +45450,10 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="4" label="VAAPI_ERROR"/>
 </enum>
 
+<enum name="VAVEAEncoderFailure" type="int">
+  <int value="0" label="VAAPI_ERROR"/>

[Ilya Sherman, 2014/06/20 20:04:30]

Is there really only a single failure type?  What information do you hope to
draw from this histogram?  If it's an error rate, what is the baseline that
you're planning to compare to?  Can that baseline be built into the histogram
instead?

[Pawel Osciak, 2014/06/20 22:28:11]

The class I'm adding reuses VaapiWrapper, which is also used by another class
for HW decode. VaapiWrapper takes a callback for reporting errors. That decode
class has a longer list of failures (Media.VAVDA.DecoderFailure,
https://code.google.com/p/chromium/codesearch#chromium/src/content/common/gpu...),
which we use to understand the usage of unimplemented features, as well as
whether vaapi backend is working fine (VAAPI_ERROR is one of the error codes in
the decode class' histogram).

The baseline for this uma in this encoder class is the number of successful
instantiations of RTCVideoEncoder, which is the
Media.RTCVideoEncoderInitEncodeSuccess. Ideally, the number of VAAPI_ERROR
should be zero if things are working properly. A higher number would indicate a
platform/driver problems in the wild that we'd have to investigate.

+</enum>
+
 <enum name="VideoCodec" type="int">
   <int value="0" label="kUnknownVideoCodec"/>
   <int value="1" label="kCodecH264"/>