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

cc/base/time_util.h

+// Copyright 2014 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.
+
+#ifndef CC_BASE_TIME_UTIL_H_
+#define CC_BASE_TIME_UTIL_H_
+
+#include <limits>
+#include "base/time/time.h"
+
+namespace cc {
+
+class CC_EXPORT TimeUtil {
+ public:
+  static double TicksInSecondsF(base::TimeTicks time) {

[ajuma, 2014/05/05 15:13:32]

A previous CL that added similar functions was rejected here:
https://codereview.chromium.org/192433002/#msg10

Also, making these functions available would seem to encourage conversions
between TimeTicks and doubles, when we should really be trying to eliminate them
all.

Alternative suggestion:
In non-test code, use the existing way of converting (that is, (ticks -
base::TimeTicks()).InSecondsF() to convert from TimeTicks to double, and
base::TimeTicks::FromInternalValue(seconds * base::Time::kMicrosecondsPerSecond)
to convert from double to TimeTicks).

For test code, where we have a large number of these conversions, add these
conversion functions to cc/test/animation_test_common.{h, cc}.

[Sikugu_, 2014/05/07 14:49:07]

Done.

+    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()) /
+           base::Time::kMicrosecondsPerSecond;
+  }
+
+  static base::TimeTicks TicksFromSecondsF(double seconds) {
+    return base::TimeTicks::FromInternalValue(
+        seconds * base::Time::kMicrosecondsPerSecond);
+  }
+};
+
+}  // namespace cc
+
+#endif  // CC_BASE_TIME_UTIL_H_