Allow BackoffEntry to be serialized and deserialized.

net/base/backoff_entry.h

Index: net/base/backoff_entry.h
diff --git a/net/base/backoff_entry.h b/net/base/backoff_entry.h
index dbc7488b7a4bd8005b5d699da8158d3a5459685c..5511d041a70e987b36fa69408b0a8470ee7de44e 100644
--- a/net/base/backoff_entry.h
+++ b/net/base/backoff_entry.h
@@ -22,7 +22,8 @@ namespace net {
 // intended for reuse in various networking scenarios.
 class NET_EXPORT BackoffEntry : NON_EXPORTED_BASE(public base::NonThreadSafe) {
  public:
-  // The set of parameters that define a back-off policy.
+  // The set of parameters that define a back-off policy. If you change this,
+  // increment SERIALIZATION_VERSION_NUMBER in backoff_entry_serializer.cc.
   struct Policy {
     // Number of initial errors (in sequence) to ignore before applying
     // exponential back-off rules.
@@ -99,9 +100,15 @@ class NET_EXPORT BackoffEntry : NON_EXPORTED_BASE(public base::NonThreadSafe) {
   int failure_count() const { return failure_count_; }
 
  private:
+  friend class BackoffEntrySerializer;
+
   // Calculates when requests should again be allowed through.
   base::TimeTicks CalculateReleaseTime() const;
 
+  // Converts time_until_release to a release time, obeying maximum_backoff_ms.
+  base::TimeTicks TimeUntilReleaseToReleaseTime(
+      base::TimeDelta time_until_release) const;

[mmenke, 2015/05/05 15:47:51]

nit:  Maybe time_until_release -> backoff (or backoff_[delta|time])?  It seems
weird to use "maximum_backoff" to limit "time_until_release".

[johnme, 2015/05/06 12:46:46]

Ok, renamed time_until_release to backoff_duration everywhere.

+
   // Equivalent to TimeTicks::Now(), using clock_ if provided.
   base::TimeTicks GetTimeTicksNow() const;