Simplify OriginTrialContext and the way it validates tokens.

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 ac84ba370b264ac7b82887079ca195419cc6ea36..72d9ae4ef8e98d050872baf04cb758e3c4ad8015 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -36823,6 +36823,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="OriginTrials.FeatureEnabled" enum="OriginTrialEnableResult">
+  <obsolete>
+    Obsolete as of Chrome 54. Sort of replaced by OriginTrials.ValidationResult.
+  </obsolete>
   <owner>chasej@chromium.org</owner>
   <owner>iclelland@chromium.org</owner>
   <summary>
@@ -36834,6 +36837,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="OriginTrials.FeatureEnabled.MessageGenerated"
     enum="OriginTrialMessageGeneratedResult">
+  <obsolete>
+    Obsolete as of Chrome 54.
+  </obsolete>
   <owner>chasej@chromium.org</owner>
   <owner>iclelland@chromium.org</owner>
   <summary>
@@ -36842,6 +36848,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="OriginTrials.ValidationResult" enum="OriginTrialTokenStatus">
+  <owner>chasej@chromium.org</owner>
+  <owner>iclelland@chromium.org</owner>
+  <summary>
+    Counts the results of token validation checks to enable experimental
+    features. The result for each token validation check is counted once per
+    token per execution context (e.g. page, worker).
+  </summary>
+</histogram>
+
 <histogram name="OSX.BluetoothAvailability" enum="BluetoothAvailability">
   <owner>erikchen@chromium.org</owner>
   <summary>
@@ -84734,6 +84750,18 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="2" label="No"/>
 </enum>
 
+<enum name="OriginTrialTokenStatus" type="int">

[iclelland, 2016/07/13 14:30:09]

If you're deprecating OriginTrialEnableResult, then we should put a comment
there suggesting that people not use it, as it is likely going to get
out-of-sync with the code.

[Marijn Kruisselbrink, 2016/07/13 19:16:08]

Done

+  <int value="0" label="Success"/>
+  <int value="1" label="NotSupported"/>
+  <int value="2" label="Insecure"/>
+  <int value="3" label="Expired"/>
+  <int value="4" label="WrongOrigin"/>
+  <int value="5" label="InvalidSignature"/>
+  <int value="6" label="Malformed"/>
+  <int value="7" label="WrongVersion"/>
+  <int value="8" label="FeatureDisabled"/>
+</enum>
+
 <enum name="OSAgnosticErrno" type="int">
   <summary>Errno values with the same meanings on Mac/Win/Linux.</summary>
   <int value="0" label="0">No error</int>