Move timing files into base/time, install forwarding headers.

base/time/clock.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.
 
 #ifndef BASE_CLOCK_H_
 #define BASE_CLOCK_H_
 
 #include "base/base_export.h"
-#include "base/time.h"
+#include "base/time/time.h"
 
 namespace base {
 
 // A Clock is an interface for objects that vend Times.  It is
 // intended to be able to test the behavior of classes with respect to
 // time.
 //
-// See DefaultClock (base/default_clock.h) for the default
+// See DefaultClock (base/time/default_clock.h) for the default
 // implementation that simply uses Time::Now().
 //
 // (An implementation that uses Time::SystemTime() should be added as
 // needed.)
 //
 // See SimpleTestClock (base/test/simple_test_clock.h) for a simple
 // test implementation.
 //
-// See TickClock (base/tick_clock.h) for the equivalent interface for
+// See TickClock (base/time/tick_clock.h) for the equivalent interface for
 // TimeTicks.
 class BASE_EXPORT Clock {
  public:
   virtual ~Clock();
 
   // Now() must be safe to call from any thread.  The caller cannot
   // make any ordering assumptions about the returned Time.  For
   // example, the system clock may change to an earlier time.
   virtual Time Now() = 0;
 };
 
 }  // namespace base
 
 #endif  // BASE_CLOCK_H_