Move BenchTimer to tools as Timer

This breaks a bunch of circular dependencies between tools and gm and bench.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/4ed75287aed6371c6e4a41ffcc78c8a49c9810ed

CQ_EXTRA_TRYBOTS=tryserver.skia:Build-Mac10.7-Clang-Arm7-Debug-iOS-Trybot,Test-Ubuntu12-ShuttleA-GTX660-x86-Debug-Trybot
R=tfarina@chromium.org, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/344213003
diff --git a/tools/timer/SysTimer_posix.cpp b/tools/timer/SysTimer_posix.cpp
new file mode 100644
index 0000000..4b7d708
--- /dev/null
+++ b/tools/timer/SysTimer_posix.cpp
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2011 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "SysTimer_posix.h"
+
+static double interval_in_ms(timespec start_clock, timespec end_clock)
+{
+    double duration_clock;
+    if ((end_clock.tv_nsec - start_clock.tv_nsec) < 0) {
+        duration_clock = (end_clock.tv_sec - start_clock.tv_sec - 1) * 1000;
+        duration_clock += (1000000000 + end_clock.tv_nsec - start_clock.tv_nsec) / 1000000.0;
+    } else {
+        duration_clock = (end_clock.tv_sec - start_clock.tv_sec) * 1000;
+        duration_clock += (end_clock.tv_nsec - start_clock.tv_nsec) / 1000000.0;
+    }
+    return duration_clock;
+}
+
+void SysTimer::startWall() {
+    if (-1 == clock_gettime(CLOCK_MONOTONIC, &fWall)) {
+        timespec none = {0, 0};
+        fWall = none;
+    }
+}
+void SysTimer::startCpu() {
+    if (-1 == clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &fCpu)) {
+        timespec none = {0, 0};
+        fCpu = none;
+    }
+}
+
+double SysTimer::endCpu() {
+    timespec end_cpu;
+    if (-1 == clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end_cpu)) {
+        timespec none = {0, 0};
+        end_cpu = none;
+    }
+    return interval_in_ms(fCpu, end_cpu);
+}
+
+double SysTimer::endWall() {
+    timespec end_wall;
+    if (-1 == clock_gettime(CLOCK_MONOTONIC, &end_wall)) {
+        timespec none = {0, 0};
+        end_wall = none;
+    }
+    return interval_in_ms(fWall, end_wall);
+}