Fix PPAPI time conversion code to handle epoch times.

ppapi/shared_impl/time_conversion_unittest.cc

 // 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.
 
 #include <math.h>
 #include <stdlib.h>
 
 #include "ppapi/shared_impl/time_conversion.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 32 matching lines @@
   EXPECT_GE(kTimeSecondsSlop, fabs(converted - event_now));
 
   // Units should be in seconds.
   base::Time one_second_from_now = now + base::TimeDelta::FromSeconds(1);
   double event_one_second_from_now = one_second_from_now.ToDoubleT();
   EXPECT_GE(kTimeSecondsSlop,
             1.0 - ppapi::EventTimeToPPTimeTicks(event_one_second_from_now) -
                 ppapi::EventTimeToPPTimeTicks(event_now));
 }
 
+TEST(TimeConversion, EpochTime) {
+  // Should be able to round-trip.
+  base::Time epoch = base::Time::UnixEpoch();
+  base::Time converted = ppapi::PPTimeToTime(TimeToPPTime(epoch));
+  EXPECT_GE(kTimeInternalValueSlop,
+            abs(static_cast<int>((converted - epoch).ToInternalValue())));
+
+  // Units should be in seconds.
+  base::Time one_second_from_epoch = epoch + base::TimeDelta::FromSeconds(1);
+  double converted_one_second_from_epoch =
+      ppapi::TimeToPPTime(one_second_from_epoch) - ppapi::TimeToPPTime(epoch);
+  EXPECT_GE(kTimeSecondsSlop, fabs(converted_one_second_from_epoch - 1));

[Scott Hess - ex-Googler, 2012/12/13 18:35:24]

I think you should have a straight up test that PPTimeToTime(0.0) returns
UnixEpoch(), or relate an offset from the epoch in seconds between PPTime and
Time, something like:
  EXPECT_EQ(PPTimeToTime(0.0) + FromSeconds(1), PPTimeToTime(1.0));

[raymes, 2012/12/14 17:28:22]

Done.

+}
+
 }  // namespace ppapi