Added UMA for usage of BudgetAPI calls.

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 9bc93150da2a4b1e2722d224bde95790dda6ec31..e876ddd1f928af89a0ec0cca6bc4df44693c9c45 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -5085,6 +5085,25 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>A bubble was given to the bubble manager but not shown.</summary>
 </histogram>
 
+<histogram name="BudgetAPI.QueryBudget" units="budget">
+  <owner>harkness@chromium.org</owner>
+  <summary>
+    Whenever the Budget API framework receives a query for the current budget,
+    this records the total budget available to the origin, which is an internal
+    Chrome value for the amount of background processing an origin can do
+    without visibly alerting the user. Scale for the budget is 0 to 100.
+  </summary>
+</histogram>
+
+<histogram name="BudgetAPI.Reserve" enum="BooleanSuccess">
+  <owner>harkness@chromium.org</owner>
+  <summary>
+    Whenever the Budget API framework receives a request to reserve budget for a
+    future background operation, this records whether the reserve request
+    succeeded or not.
+  </summary>
+</histogram>
+
 <histogram name="Canvas.ContextType" enum="CanvasContextType">
   <owner>junov@chromium.org</owner>
   <owner>kbr@chromium.org</owner>