More accurate implementation of watched thread time for Gpu Watchdog.

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 coordinated universal time (UTC),
 // internally represented as microseconds (s/1,000,000) since the Windows epoch
 // (1601-01-01 00:00:00 UTC). System-dependent clock interface routines are
 // defined in time_PLATFORM.cc. Note that values for Time may skew and jump
 // around as the operating system makes adjustments to synchronize (e.g., with
 // NTP servers). Thus, client code that uses the Time class must account for
@@ skipping 56 matching lines @@
 
 #if defined(OS_POSIX)
 #include <unistd.h>
 #include <sys/time.h>
 #endif
 
 #if defined(OS_WIN)
 // For FILETIME in FromFileTime, until it moves to a new converter class.
 // See TODO(iyengar) below.
 #include <windows.h>
-
 #include "base/gtest_prod_util.h"
 #endif
 
 namespace base {
 
+class PlatformThreadHandle;
 class TimeDelta;
 
 // The functions in the time_internal namespace are meant to be used only by the
 // time classes and functions.  Please use the math operators defined in the
 // time classes instead.
 namespace time_internal {
 
 // Add or subtract |value| from a TimeDelta. The int64_t argument and return
 // value are in terms of a microsecond timebase.
 BASE_EXPORT int64_t SaturatedAdd(TimeDelta delta, int64_t value);
@@ skipping 649 matching lines @@
 
   // Returns thread-specific CPU-time on systems that support this feature.
   // Needs to be guarded with a call to IsSupported(). Use this timer
   // to (approximately) measure how much time the calling thread spent doing
   // actual work vs. being de-scheduled. May return bogus results if the thread
   // migrates to another CPU between two calls. Returns an empty ThreadTicks
   // object until the initialization is completed. If a clock reading is
   // absolutely needed, call WaitUntilInitialized() before this method.
   static ThreadTicks Now();
 
+#if defined(OS_WIN)
+  // Similar to Now() above except this returns thread-specific CPU time for an
+  // arbitrary thread. All comments for Now() method above apply apply to this
+  // method as well.
+  static ThreadTicks GetForThread(const PlatformThreadHandle& thread_handle);
+#endif
+
  private:
   friend class time_internal::TimeBase<ThreadTicks>;
 
-  // Please use Now() to create a new object. This is for internal use
-  // and testing.
+  // Please use Now() or GetForThread() to create a new object. This is for
+  // internal use and testing.
   explicit ThreadTicks(int64_t us) : TimeBase(us) {}
 
 #if defined(OS_WIN)
   FRIEND_TEST_ALL_PREFIXES(TimeTicks, TSCTicksPerSecond);
 
   // Returns the frequency of the TSC in ticks per second, or 0 if it hasn't
   // been measured yet. Needs to be guarded with a call to IsSupported().
   // This method is declared here rather than in the anonymous namespace to
   // allow testing.
   static double TSCTicksPerSecond();
 
   static bool IsSupportedWin();
   static void WaitUntilInitializedWin();
 #endif
 };
 
 // For logging use only.
 BASE_EXPORT std::ostream& operator<<(std::ostream& os, ThreadTicks time_ticks);
 
 }  // namespace base
 
 #endif  // BASE_TIME_TIME_H_