Custom Tabs: add speculation status histograms.

tools/metrics/histograms/enums.xml

Index: tools/metrics/histograms/enums.xml
diff --git a/tools/metrics/histograms/enums.xml b/tools/metrics/histograms/enums.xml
index c3c39ff4a444963a3db8320294f4be703aa7ce71..dba0a4d5cf2bf3287350e949146a3f6ad11cf5c7 100644
--- a/tools/metrics/histograms/enums.xml
+++ b/tools/metrics/histograms/enums.xml
@@ -6725,6 +6725,27 @@ uploading your change for review.  These are checked by presubmit scripts.
   <int value="2" label="Has enough SCTs"/>
 </enum>
 
+<enum name="CustomTabsSpeculationStatusOnStart" type="int">
+  <int value="0"
+      label="Speculation allowed. If started, the kind will also be recorded"/>
+  <int value="1" label="Prefetch kind of speculation started"/>
+  <int value="2" label="Prerender kind of speculation started"/>
+  <int value="3" label="Background Tab kind of speculation started"/>
+  <int value="4" label="Prerender speculation allowed, but not started"/>
+  <int value="5" label="Not allowed: Device class"/>
+  <int value="6" label="Not allowed: Block 3rd party cookies"/>
+  <int value="7" label="Not allowed: Network prediction disabled"/>
+  <int value="8" label="Not allowed: Data reduction enabled"/>
+  <int value="9" label="Not allowed: Network metered"/>
+</enum>
+
+<enum name="CustomTabsSpeculationStatusOnSwap" type="int">
+  <int value="0" label="Background Tab Swapped In"/>
+  <int value="1" label="Background Tab Not Matched"/>
+  <int value="2" label="Prerender Swapped In"/>
+  <int value="3" label="Prerender Not Matched"/>
+</enum>
+
 <enum name="D3D11FeatureLevel" type="int">
   <int value="0" label="Unknown"/>
   <int value="1" label="No D3D11 DLL"/>