Revert of SkTime::GetNSecs() (patchset #10 id:180001 of https://codereview.chromium.org/1422513003/ )

Reason for revert:
https://codereview.chromium.org/1412453006

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
>
> CQ_EXTRA_TRYBOTS=client.skia.compile:Build-Ubuntu-GCC-x86_64-Debug-CrOS_Link-Trybot
>
> Committed: https://skia.googlesource.com/skia/+/a1840d50e29fd95e4df2d1168fe54c34c2a5c30c

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

Review URL: https://codereview.chromium.org/1417753003

4 files changed, 36 insertions, 35 deletions

diff --git a/src/animator/SkTime.cpp b/src/animator/SkTime.cpp
index 560ccd2fc8..a4e035bd1e 100644
--- a/src/animator/SkTime.cpp
+++ b/src/animator/SkTime.cpp
@@ -28,6 +28,15 @@ void SkTime::GetDateTime(DateTime* t) {
     }
 }
 
+SkMSec SkTime::GetMSecs() {
+#ifdef SK_DEBUG
+    if (gForceTickCount != (SkMSec) -1) {
+        return gForceTickCount;
+    }
+#endif
+    return ::GetTickCount();
+}
+
 #elif defined(xSK_BUILD_FOR_MAC)
 
 #include <time.h>
@@ -49,4 +58,13 @@ void SkTime::GetDateTime(DateTime* t) {
     }
 }
 
+SkMSec SkTime::GetMSecs() {
+    UnsignedWide    wide;
+    ::Microseconds(&wide);
+
+    int64_t s = ((int64_t)wide.hi << 32) | wide.lo;
+    s = (s + 500) / 1000;   // rounded divide
+    return (SkMSec)s;
+}
+
 #endif
diff --git a/src/core/SkTime.cpp b/src/core/SkTime.cpp
index 03970aa824..fa6c04447d 100644
--- a/src/core/SkTime.cpp
+++ b/src/core/SkTime.cpp
@@ -5,7 +5,6 @@
  * found in the LICENSE file.
  */
 
-#include "SkOncePtr.h"
 #include "SkString.h"
 #include "SkTime.h"
 
@@ -23,37 +22,3 @@ void SkTime::DateTime::toISO8601(SkString* dst) const {
                     timeZoneMinutes);
     }
 }
-
-// TODO: use rdtscp when (runtime) available
-// TODO: use std::chrono when (compile-time) available
-
-#if defined(_MSC_VER)
-    #include <intrin.h>
-    SK_DECLARE_STATIC_ONCE_PTR(double, ns_per_tick);
-    double SkTime::GetNSecs() {
-        uint64_t ticks = __rdtsc();
-        return ticks * *ns_per_tick.get([]{
-            LARGE_INTEGER khz;  // The docs say this returns Hz, but it returns KHz.
-            QueryPerformanceFrequency(&khz);
-            return new double(1e6 / khz.QuadPart);
-        });
-    }
-#elif defined(__MACH__)
-    #include <mach/mach_time.h>
-    SK_DECLARE_STATIC_ONCE_PTR(double, ns_per_tick);
-    double SkTime::GetNSecs() {
-        uint64_t ticks = mach_absolute_time();
-        return ticks * *ns_per_tick.get([]{
-            mach_timebase_info_data_t timebase;
-            (void)mach_timebase_info(&timebase);
-            return new double(timebase.numer * 1.0 / timebase.denom);
-        });
-    }
-#else
-    #include <time.h>
-    double SkTime::GetNSecs() {
-        struct timespec ts = {0, 0};
-        (void)clock_gettime(CLOCK_MONOTONIC, &ts);
-        return ts.tv_sec * 1e9 + ts.tv_nsec;
-    }
-#endif
diff --git a/src/ports/SkTime_Unix.cpp b/src/ports/SkTime_Unix.cpp
index 1ea3b8fbd0..ec96bb8a90 100644
--- a/src/ports/SkTime_Unix.cpp
+++ b/src/ports/SkTime_Unix.cpp
@@ -34,3 +34,10 @@ void SkTime::GetDateTime(DateTime* dt)
         dt->fSecond     = SkToU8(tstruct->tm_sec);
     }
 }
+
+SkMSec SkTime::GetMSecs()
+{
+    struct timeval tv;
+    gettimeofday(&tv, nullptr);
+    return (SkMSec) (tv.tv_sec * 1000 + tv.tv_usec / 1000 ); // microseconds to milliseconds
+}
diff --git a/src/ports/SkTime_win.cpp b/src/ports/SkTime_win.cpp
index 2bd5062c3c..19f4695a86 100644
--- a/src/ports/SkTime_win.cpp
+++ b/src/ports/SkTime_win.cpp
@@ -39,3 +39,14 @@ void SkTime::GetDateTime(DateTime* dt)
         dt->fSecond     = SkToU8(st.wSecond);
     }
 }
+
+SkMSec SkTime::GetMSecs()
+{
+    FILETIME        ft;
+    LARGE_INTEGER   li;
+    GetSystemTimeAsFileTime(&ft);
+    li.LowPart  = ft.dwLowDateTime;
+    li.HighPart = ft.dwHighDateTime;
+    __int64 t  = li.QuadPart;       /* In 100-nanosecond intervals */
+    return (SkMSec)(t / 10000);               /* In milliseconds */
+}