Refactor net::BackoffEntry to not require subclassing

chrome/browser/captive_portal/captive_portal_service.cc

Index: chrome/browser/captive_portal/captive_portal_service.cc
diff --git a/chrome/browser/captive_portal/captive_portal_service.cc b/chrome/browser/captive_portal/captive_portal_service.cc
index 6098d80e8a4294da5aef8756163adcd688db26d8..baf2dfd828008942965e355c95fa4ae8ca07fba7 100644
--- a/chrome/browser/captive_portal/captive_portal_service.cc
+++ b/chrome/browser/captive_portal/captive_portal_service.cc
@@ -10,6 +10,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
+#include "base/time/tick_clock.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/pref_names.h"
@@ -138,22 +139,20 @@ bool ShouldDeferToNativeCaptivePortalDetection() {
 CaptivePortalService::TestingState CaptivePortalService::testing_state_ =
     NOT_TESTING;
 
-class CaptivePortalService::RecheckBackoffEntry : public net::BackoffEntry {
+class CaptivePortalService::RecheckTickClock : public base::TickClock {
  public:
-  explicit RecheckBackoffEntry(CaptivePortalService* captive_portal_service)
-      : net::BackoffEntry(
-            &captive_portal_service->recheck_policy().backoff_policy),
-        captive_portal_service_(captive_portal_service) {
+  explicit RecheckTickClock(CaptivePortalService* captive_portal_service)
+      : captive_portal_service_(captive_portal_service) {
   }
 
- private:
-  base::TimeTicks ImplGetTimeNow() const override {
-    return captive_portal_service_->GetCurrentTimeTicks();
+  base::TimeTicks NowTicks() override {
+    return captive_portal_service_->NowTicks();
   }
 
+ private:
   CaptivePortalService* captive_portal_service_;
 
-  DISALLOW_COPY_AND_ASSIGN(RecheckBackoffEntry);
+  DISALLOW_COPY_AND_ASSIGN(RecheckTickClock);
 };
 
 CaptivePortalService::RecheckPolicy::RecheckPolicy()
@@ -260,7 +259,7 @@ void CaptivePortalService::OnPortalDetectionCompleted(
 
   CaptivePortalResult result = results.result;
   const base::TimeDelta& retry_after_delta = results.retry_after_delta;
-  base::TimeTicks now = GetCurrentTimeTicks();
+  base::TimeTicks now = NowTicks();
 
   // Record histograms.
   UMA_HISTOGRAM_ENUMERATION("CaptivePortal.DetectResult",
@@ -316,7 +315,7 @@ void CaptivePortalService::Shutdown() {
     RecordRepeatHistograms(
         last_detection_result_,
         num_checks_with_same_result_,
-        GetCurrentTimeTicks() - first_check_time_with_same_result_);
+        NowTicks() - first_check_time_with_same_result_);
   }
 }
 
@@ -348,7 +347,9 @@ void CaptivePortalService::ResetBackoffEntry(CaptivePortalResult result) {
         recheck_policy_.initial_backoff_no_portal_ms;
   }
 
-  backoff_entry_.reset(new RecheckBackoffEntry(this));
+  backoff_entry_.reset(new net::BackoffEntry(
+      &recheck_policy().backoff_policy,
+      this));
 }
 
 void CaptivePortalService::UpdateEnabledState() {
@@ -386,7 +387,7 @@ void CaptivePortalService::UpdateEnabledState() {
   }
 }
 
-base::TimeTicks CaptivePortalService::GetCurrentTimeTicks() const {
+base::TimeTicks CaptivePortalService::NowTicks() {
   if (time_ticks_for_testing_.is_null())
     return base::TimeTicks::Now();
   else