Revert of SkTime::GetNSecs()

tools/timer/Timer.cpp

Index: tools/timer/Timer.cpp
diff --git a/tools/timer/Timer.cpp b/tools/timer/Timer.cpp
index 28841cdc846f9a93efd02dbb696c36c17b245169..b59988ca2642f5f3330d05ba849cdde8c4c49e0d 100644
--- a/tools/timer/Timer.cpp
+++ b/tools/timer/Timer.cpp
@@ -5,6 +5,52 @@
  * found in the LICENSE file.
  */
 #include "Timer.h"
+
+Timer::Timer(SkGLContext* gl)
+        : fCpu(-1.0)
+        , fWall(-1.0)
+        , fTruncatedCpu(-1.0)
+        , fTruncatedWall(-1.0)
+        , fGpu(-1.0)
+#if SK_SUPPORT_GPU
+        , fGpuTimer(gl)
+#endif
+        {}
+
+void Timer::start() {
+    fSysTimer.startWall();
+    fTruncatedSysTimer.startWall();
+#if SK_SUPPORT_GPU
+    fGpuTimer.start();
+#endif
+    fSysTimer.startCpu();
+    fTruncatedSysTimer.startCpu();
+}
+
+void Timer::end() {
+    fCpu = fSysTimer.endCpu();
+#if SK_SUPPORT_GPU
+    //It is important to stop the cpu clocks first,
+    //as the following will cpu wait for the gpu to finish.
+    fGpu = fGpuTimer.end();
+#endif
+    fWall = fSysTimer.endWall();
+}
+
+void Timer::truncatedEnd() {
+    fTruncatedCpu = fTruncatedSysTimer.endCpu();
+    fTruncatedWall = fTruncatedSysTimer.endWall();
+}
+
+WallTimer::WallTimer() : fWall(-1.0) {}
+
+void WallTimer::start() {
+    fSysTimer.startWall();
+}
+
+void WallTimer::end() {
+    fWall = fSysTimer.endWall();
+}
 
 SkString HumanizeMs(double ms) {
     if (ms > 60e+3)  return SkStringPrintf("%.3gm", ms/60e+3);