Use a monotonic clock (TimeTicks) to report network times to WebCore.

base/time.h

 // Copyright (c) 2011 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.
 
 // Time represents an absolute point in time, internally represented as
 // microseconds (s/1,000,000) since a platform-dependent epoch.  Each
 // platform's epoch, along with other system-dependent clock interface
 // routines, is defined in time_PLATFORM.cc.
 //
 // TimeDelta represents a duration of time, internally represented in
@@ skipping 474 matching lines @@
   // Returns true if this object has not been initialized.
   bool is_null() const {
     return ticks_ == 0;
   }
 
   // Returns the internal numeric value of the TimeTicks object.
   int64 ToInternalValue() const {
     return ticks_;
   }
 
+  // Converts an integer value representing TimeTicks to a class. This is used
+  // when deserializing a |TimeTicks| structure, using a value that originated
+  // from |TimeTicks::ToInternalValue()|.
+  static TimeTicks FromInternalValue(int64 ticks) {
+    return TimeTicks(ticks);
+  }

[wtc, 2011/08/26 21:55:41]

It is safe to deserialize this way only if all the int64
ticks values have the same "origin" (time 0), which is
probably true only if they come from the same process.

Also, this static method is equivalent to the protected
constructor on lines 555-556 below.  Why don't you just
make that constructor public?

[James Simonsen, 2011/08/26 22:34:29]

Pavel and I discussed this earlier. All of the platforms use a system-wide clock
for TimeTicks. So, all processes use the same origin (roughly time since last
reboot).
I copied it from Time. I've now copied the comment that went with that one too.
I don't have an opinion either way though, so if you'd like TimeTicks to have a
different interface than Time, let me know.

[wtc, 2011/08/26 23:39:15]

If you are relying on this fact, and are deserializing
TimeTicks values that come from different processes,
you need to document this property in the class TimeTicks.
I see.  What you have is fine.

+
   TimeTicks& operator=(TimeTicks other) {
     ticks_ = other.ticks_;
     return *this;
   }
 
   // Compute the difference between two times.
   TimeDelta operator-(TimeTicks other) const {
     return TimeDelta(ticks_ - other.ticks_);
   }
 
@@ skipping 52 matching lines @@
 #endif
 };
 
 inline TimeTicks TimeDelta::operator+(TimeTicks t) const {
   return TimeTicks(t.ticks_ + delta_);
 }
 
 }  // namespace base
 
 #endif  // BASE_TIME_H_