Blink Platform: Remove time functions from Platform.

third_party/WebKit/Source/wtf/CurrentTime.cpp

Index: third_party/WebKit/Source/wtf/CurrentTime.cpp
diff --git a/third_party/WebKit/Source/wtf/CurrentTime.cpp b/third_party/WebKit/Source/wtf/CurrentTime.cpp
index c29636f98c9cc551ec735476ecca99893408a8a3..dc64e33663f4e558739a699d96be1a4519a2098d 100644
--- a/third_party/WebKit/Source/wtf/CurrentTime.cpp
+++ b/third_party/WebKit/Source/wtf/CurrentTime.cpp
@@ -30,29 +30,31 @@
 
 #include "wtf/CurrentTime.h"
 
-namespace WTF {
+#include "base/time/time.h"
 
-static TimeFunction currentTimeFunction;
-static TimeFunction monotonicallyIncreasingTimeFunction;
+namespace WTF {
 
-void setCurrentTimeFunction(TimeFunction func)
-{
-    currentTimeFunction = func;
-}
+static TimeFunction mockTimeFunctionForTesting = nullptr;
 
-void setMonotonicallyIncreasingTimeFunction(TimeFunction func)
+double currentTime()

[haraken, 2016/02/09 09:13:58]

Given that this method is performance-sensitive, I'd inline it.

[Yuta Kitamura, 2016/02/09 09:54:56]

Hm, that would make mockTimeFunctionForTesting public.
Is that fine for you?

[Yuta Kitamura, 2016/02/15 07:26:38]

According to my local testing, inlining had a negative impact
on perf.now() throughput, so I left these out-of-line.

 {
-    monotonicallyIncreasingTimeFunction = func;
+    if (mockTimeFunctionForTesting)

[haraken, 2016/02/09 09:13:58]

I'd add UNLIKELY.

[Yuta Kitamura, 2016/02/09 09:54:57]

I'm almost certain that PGO (profile-guided optimization)
can do that for us; generally speaking, I think (UN)LIKELY
macros should be added only after the profilers determine
the bottlenecks...

[tkent, 2016/02/10 00:04:39]

I agree with yutak.

+        return mockTimeFunctionForTesting();
+    return base::Time::Now().ToDoubleT();
 }
 
-double currentTime()
+double monotonicallyIncreasingTime()

[haraken, 2016/02/09 09:13:58]

Ditto.

 {
-    return (*currentTimeFunction)();
+    if (mockTimeFunctionForTesting)
+        return mockTimeFunctionForTesting();
+    return base::TimeTicks::Now().ToInternalValue() / static_cast<double>(base::Time::kMicrosecondsPerSecond);
 }
 
-double monotonicallyIncreasingTime()
+TimeFunction setTimeFunctionsForTesting(TimeFunction newFunction)
 {
-    return (*monotonicallyIncreasingTimeFunction)();
+    TimeFunction oldFunction = mockTimeFunctionForTesting;
+    mockTimeFunctionForTesting = newFunction;
+    return oldFunction;
 }
 
 } // namespace WTF