Add metrics to measure time elapsed between form load and form submission with or without Autofill.

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 42 matching lines @@
   }
 
   // Converts units of time to TimeDeltas.
   static TimeDelta FromDays(int64 days);
   static TimeDelta FromHours(int64 hours);
   static TimeDelta FromMinutes(int64 minutes);
   static TimeDelta FromSeconds(int64 secs);
   static TimeDelta FromMilliseconds(int64 ms);
   static TimeDelta FromMicroseconds(int64 us);
 
+  // Converts an integer value representing TimeDelta to a class. This is used
+  // when deserializing a |TimeDelta| structure, using a value known to be
+  // compatible. It is not provided as a constructor because the integer type
+  // may be unclear from the perspective of a caller.
+  static TimeDelta FromInternalValue(int64 delta) {
+    return TimeDelta(delta);
+  }
+
   // Returns the internal numeric value of the TimeDelta object. Please don't
   // use this and do arithmetic on it, as it is more error prone than using the
   // provided operators.
+  // For serializing, use FromInternalValue to reconstitute.
   int64 ToInternalValue() const {
     return delta_;
   }
 
 #if defined(OS_POSIX)
   struct timespec ToTimeSpec() const;
 #endif
 
   // Returns the time delta in some unit. The F versions return a floating
   // point value, the "regular" versions return a rounded-down value.
@@ skipping 404 matching lines @@
   // Returns true if the high resolution clock is working on this system.
   // This is only for testing.
   static bool IsHighResClockWorking();
 #endif
 
   // Returns true if this object has not been initialized.
   bool is_null() const {
     return ticks_ == 0;
   }
 
+  // Converts an integer value representing TimeTicks to a class. This is used
+  // when deserializing a |TimeTicks| structure, using a value known to be
+  // compatible. It is not provided as a constructor because the integer type
+  // may be unclear from the perspective of a caller.
+  static TimeTicks FromInternalValue(int64 ticks) {
+    return TimeTicks(ticks);
+  }
+
   // Returns the internal numeric value of the TimeTicks object.
+  // For serializing, use FromInternalValue to reconstitute.
   int64 ToInternalValue() const {
     return ticks_;
   }
 
   TimeTicks& operator=(TimeTicks other) {
     ticks_ = other.ticks_;
     return *this;
   }
 
   // Compute the difference between two times.
@@ skipping 56 matching lines @@
 #endif
 };
 
 inline TimeTicks TimeDelta::operator+(TimeTicks t) const {
   return TimeTicks(t.ticks_ + delta_);
 }
 
 }  // namespace base
 
 #endif  // BASE_TIME_H_