Revert of SkTime::GetNSecs() (patchset #9 id:160001 of https://codereview.chromium.org/1422513003/ )

Reason for revert:
broke chromeos

Original issue's description:
> SkTime::GetNSecs()
>
>    - Move high-precision wall timers from tools/timer to SkTime.
>    - Implement SkTime::GetMSecs() in terms of SkTime::GetNSecs().
>    - Delete unused tools/timer code.
>
> I have no idea what's going on there in src/animator.
> I don't intend to investigate.
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/70084cbc16ee8162649f2601377feb6e49de0217

TBR=reed@google.com,mtklein@google.com,mtklein@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/1420923003

1 files changed, 55 insertions, 5 deletions

diff --git a/tools/timer/Timer.h b/tools/timer/Timer.h
index 446eb254fd..9557596248 100644
--- a/tools/timer/Timer.h
+++ b/tools/timer/Timer.h
@@ -7,18 +7,68 @@
 #ifndef Timer_DEFINED
 #define Timer_DEFINED
 
-#include "SkString.h"
-#include "SkTime.h"
 #include "SkTypes.h"
+#include "SkString.h"
+
+#if defined(SK_BUILD_FOR_WIN32)
+    #include "SysTimer_windows.h"
+#elif defined(SK_BUILD_FOR_MAC) || defined(SK_BUILD_FOR_IOS)
+    #include "SysTimer_mach.h"
+#elif defined(SK_BUILD_FOR_UNIX) || defined(SK_BUILD_FOR_ANDROID)
+    #include "SysTimer_posix.h"
+#endif
+
+#if SK_SUPPORT_GPU
+    #include "GpuTimer.h"
+#endif
+
+class SkGLContext;
+
+/**
+ * SysTimers and GpuTimers are implemented orthogonally.
+ * This class combines 2 SysTimers and a GpuTimer into one single,
+ * platform specific Timer with a simple interface. The truncated
+ * timer doesn't include the time required for the GPU to finish
+ * its rendering. It should always be <= the un-truncated system
+ * times and (for GPU configurations) can be used to roughly (very
+ * roughly) gauge the GPU load/backlog.
+ */
+class Timer {
+public:
+    explicit Timer(SkGLContext* gl = nullptr);
+
+    void start();
+    void truncatedEnd();
+    void end();
+
+    // All times in milliseconds.
+    double fCpu;
+    double fWall;
+    double fTruncatedCpu;
+    double fTruncatedWall;
+    double fGpu;
 
+private:
+    SysTimer fSysTimer;
+    SysTimer fTruncatedSysTimer;
+#if SK_SUPPORT_GPU
+    GpuTimer fGpuTimer;
+#endif
+};
+
+// Same as Timer above, supporting only fWall but with much lower overhead.
+// (Typically, ~30ns instead of Timer's ~1us.)
 class WallTimer {
 public:
-    WallTimer() : fWall(-1) {}
+    WallTimer();
 
-    void start() { fWall = SkTime::GetNSecs(); }
-    void end()   { fWall = (SkTime::GetNSecs() - fWall) * 1e-6; }
+    void start();
+    void end();
 
     double fWall;  // Milliseconds.
+
+private:
+    SysTimer fSysTimer;
 };
 
 SkString HumanizeMs(double);