CC::Animations should use TimeTicks & TimeDelta to represent time

base/time/time.h

 // Copyright (c) 2012 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 the Windows epoch (1601-01-01 00:00:00 UTC)
 // (See http://crbug.com/14734).  System-dependent clock interface routines are
 // defined in time_PLATFORM.cc.
 //
 // TimeDelta represents a duration of time, internally represented in
@@ skipping 647 matching lines @@
   // value for the duration of the application, but will be different in future
   // application runs.
   static TimeTicks UnixEpoch();
 
   // Returns the internal numeric value of the TimeTicks object.
   // For serializing, use FromInternalValue to reconstitute.
   int64 ToInternalValue() const {
     return ticks_;
   }
 
+  static double InSecondsF(TimeTicks time) {
+    if (time.ToInternalValue() == std::numeric_limits<int64>::max()) {
+      // Preserve max to prevent overflow.
+      return std::numeric_limits<int>::max();
+    }
+    return static_cast<double>(time.ToInternalValue()) /
+           Time::kMicrosecondsPerSecond;
+  }
+
+  static TimeTicks FromSeconds(double seconds) {
+    return TimeTicks::FromInternalValue(seconds * Time::kMicrosecondsPerSecond);
+  }

[ajuma, 2014/04/24 20:41:36]

It's not obvious to me whether these are a good idea (since TimeTicks seems to
go out of its way to avoid committing to the units that its internal value
represents). Since the rest of the CL relies heavily on this, I'd suggest
putting these up for review separately first.

+
   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_TIME_H_