Added UMA for usage of BudgetAPI calls.

chrome/browser/budget_service/budget_manager.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/budget_service/budget_manager.h"
 
 #include <stdint.h>
 
 #include "base/callback.h"
 #include "base/memory/ptr_util.h"
@@ skipping 56 matching lines @@
   return SiteEngagementScore::kMaxPoints + 1.0;
 }
 
 void BudgetManager::GetBudget(const url::Origin& origin,
                               const GetBudgetCallback& callback) {
   if (origin.unique() || !content::IsOriginSecure(origin.GetURL())) {
     callback.Run(blink::mojom::BudgetServiceErrorType::NOT_SUPPORTED,
                  mojo::Array<blink::mojom::BudgetStatePtr>());
     return;
   }
-  db_.GetBudgetDetails(origin, callback);
+  db_.GetBudgetDetails(origin,
+                       base::Bind(&BudgetManager::DidGetBudget,
+                                  weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void BudgetManager::Reserve(const url::Origin& origin,
                             blink::mojom::BudgetOperationType type,
                             const ReserveCallback& callback) {
   if (origin.unique() || !content::IsOriginSecure(origin.GetURL())) {
     callback.Run(blink::mojom::BudgetServiceErrorType::NOT_SUPPORTED,
                  false /* success */);
     return;
   }
@@ skipping 27 matching lines @@
     return;
   }
 
   // If there wasn't a reservation already, try to directly consume budget.
   // The callback will return directly to the caller.
   db_.SpendBudget(origin, GetCost(type),
                   base::Bind(&BudgetManager::DidConsume,
                              weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
+void BudgetManager::DidGetBudget(
+    const GetBudgetCallback& callback,
+    const blink::mojom::BudgetServiceErrorType error,
+    mojo::Array<blink::mojom::BudgetStatePtr> budget) {
+  // If there was an error, just record a budget of 0, so the API query is still
+  // counted.
+  double budget_at = error != blink::mojom::BudgetServiceErrorType::NONE
+                         ? 0
+                         : budget[0]->budget_at;

[Alexei Svitkine (slow), 2016/12/01 18:25:10]

Nit: This looks a bit messy to me. How about:

double budget_at = 0;
if (error == blink::mojom::BudgetServiceErrorType::NONE)
  budget_at = budget[0]->budget_at;

[harkness, 2016/12/02 13:12:38]

Done.

+  UMA_HISTOGRAM_COUNTS_100("BudgetAPI.QueryBudget", budget_at);
+
+  callback.Run(error, std::move(budget));
+}
+
 void BudgetManager::DidConsume(const ConsumeCallback& callback,
                                blink::mojom::BudgetServiceErrorType error,
                                bool success) {
   // The caller of Consume only cares whether it succeeded or failed and not
   // why. So, only return a combined bool.
   if (error != blink::mojom::BudgetServiceErrorType::NONE) {
     callback.Run(false /* success */);
     return;
   }
   callback.Run(success);
 }
 
 void BudgetManager::DidReserve(const url::Origin& origin,
                                const ReserveCallback& callback,
                                blink::mojom::BudgetServiceErrorType error,
                                bool success) {
   // If the call succeeded, write the new reservation into the map.
   if (success && error == blink::mojom::BudgetServiceErrorType::NONE)
     reservation_map_[origin]++;
 
+  UMA_HISTOGRAM_BOOLEAN("BudgetAPI.Reserve", success);
+
   callback.Run(error, success);
 }