network_time_tracker: add temporary time protocol.

components/network_time/network_time_tracker.h

Index: components/network_time/network_time_tracker.h
diff --git a/components/network_time/network_time_tracker.h b/components/network_time/network_time_tracker.h
index 7f2eb8792031d2cf56c13c17dda1b49909a0e000..f3bfffc165447e57ebc500f0f90a17c758a6c1cb 100644
--- a/components/network_time/network_time_tracker.h
+++ b/components/network_time/network_time_tracker.h
@@ -7,17 +7,31 @@
 
 #include <memory>
 
+#include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/clock.h"
 #include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "net/url_request/url_fetcher_delegate.h"
+#include "net/url_request/url_request_context_getter.h"

[Ryan Sleevi, 2016/04/29 22:54:16]

You forward declare this, no need for the header.

[mab, 2016/04/29 23:30:09]

Actually it's the forward declaration that has to go: scoped_refptr requires the
definition.

[Ryan Sleevi, 2016/04/29 23:35:30]

It doesn't require it in this header, it requires it in the place you
instantiate the NetworkTimeTracker. Because your ctor/dtor are out of line, it's
fine, but when a callsite attempts to pass a by-value scoped_refptr<>, it needs
to know how to handle the dtor for the dependent type.

So the forward declaration can stay, but you'd need to make sure to include the
url_request_context_getter header in the place you're forwarding it from (e.g.
the SystemURLRequestContext), since that code can *also* forward declare when
it's returning by-value.

[mab, 2016/04/30 00:37:19]

OK, done.  

+#include "url/gurl.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
 namespace base {
 class TickClock;
-}
+}  // namespace base
+
+namespace client_update_protocol {
+class Ecdsa;
+}  // namespace client_udpate_protocol
+
+namespace net {
+class URLFetcher;
+class URLRequestContextGetter;
+}  // namespace net
 
 namespace network_time {
 
@@ -30,14 +44,18 @@ const int64_t kTicksResolutionMs = 1;  // Assume 1ms for non-windows platforms.
 
 // A class that receives network time updates and can provide the network time
 // for a corresponding local time. This class is not thread safe.
-class NetworkTimeTracker {
+class NetworkTimeTracker : public net::URLFetcherDelegate {
  public:
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
+  // Constructor.  Arguments may be stubbed out for tests.  |getter|, if not
+  // null, will cause automatic queries to a time server.  Otherwise, time is
+  // available only if |UpdateNetworkTime| is called.
   NetworkTimeTracker(std::unique_ptr<base::Clock> clock,
                      std::unique_ptr<base::TickClock> tick_clock,
-                     PrefService* pref_service);
-  ~NetworkTimeTracker();
+                     PrefService* pref_service,
+                     scoped_refptr<net::URLRequestContextGetter> getter);
+  ~NetworkTimeTracker() override;
 
   // Sets |network_time| to an estimate of the true time.  Returns true if time
   // is available, and false otherwise.  If |uncertainty| is non-NULL, it will
@@ -62,6 +80,39 @@ class NetworkTimeTracker {
                          base::TimeTicks post_time);
 
  private:
+  friend class NetworkTimeTrackerTest;
+  FRIEND_TEST_ALL_PREFIXES(NetworkTimeTrackerTest, UpdateFromNetwork);
+  FRIEND_TEST_ALL_PREFIXES(NetworkTimeTrackerTest, NoNetworkQueryWhileSynced);
+  FRIEND_TEST_ALL_PREFIXES(NetworkTimeTrackerTest,
+                           UpdateFromNetworkBadSignature);
+  FRIEND_TEST_ALL_PREFIXES(NetworkTimeTrackerTest,
+                           UpdateFromNetworkServerError);
+  FRIEND_TEST_ALL_PREFIXES(NetworkTimeTrackerTest,
+                           UpdateFromNetworkLargeResponse);
+
+  void SetMaxResponseSize(size_t limit);   // For testing.
+  void SetTimeServerURL(const GURL& url);  // For testing.
+
+  // If synchronization has been lost, sends a query to the secure time service.
+  // Upon response, execution resumes in |OnURLFetchComplete|.
+  void QueryTimeService();
+
+  // net::URLFetcherDelegate:
+  // Called to process responses from the secure time service.
+  void OnURLFetchComplete(const net::URLFetcher* source) override;
+
+  // Sets the next time query to be run at the specified time.
+  void QueueTimeQuery(base::TimeDelta delay);
+
+  // State variables for internally-managed secure time service queries.
+  GURL server_url_;
+  size_t max_response_size_;
+  base::RepeatingTimer query_timer_;
+  scoped_refptr<net::URLRequestContextGetter> getter_;
+  std::unique_ptr<net::URLFetcher> time_fetcher_;
+  base::TimeTicks fetch_started_;
+  std::unique_ptr<client_update_protocol::Ecdsa> query_signer_;
+
   // The |Clock| and |TickClock| are used to sanity-check one another, allowing
   // the NetworkTimeTracker to notice e.g. suspend/resume events and clock
   // resets.