Enabling augmenting callback with Location

base/profiler/scoped_tracker.cc

Index: base/profiler/scoped_tracker.cc
diff --git a/base/profiler/scoped_tracker.cc b/base/profiler/scoped_tracker.cc
index 5cd0bcae34984d1d99017ccb699d7dbe48409439..7f378185f74ce68b45f4918368314030ee4735c3 100644
--- a/base/profiler/scoped_tracker.cc
+++ b/base/profiler/scoped_tracker.cc
@@ -4,12 +4,21 @@
 
 #include "base/profiler/scoped_tracker.h"
 
+#include "base/bind.h"
+
 namespace tracked_objects {
 
 namespace {
 
 ScopedProfile::Mode g_scoped_profile_mode = ScopedProfile::DISABLED;
 
+// Executes |callback|, augmenting it with provided |location|.
+void ExecuteAndAugmentCallback(const Location& location,

[Ilya Sherman, 2014/10/29 00:23:00]

nit: I find the "augment" part of this name confusing.  WDYT of
"ExecuteAndTrackCallback"?

[vadimt, 2014/10/29 00:52:21]

Done.

+                               const base::Closure& callback) {
+  ScopedProfile tracking_profile(location);

[Ilya Sherman, 2014/10/29 00:23:00]

Hmm, why not use a ScopedTracker here instead?

[vadimt, 2014/10/29 00:52:21]

ScopedTracker checks if tracking is enabled and calls ScopedProfile. Since
TrackCallback already checks g_scoped_profile_mode, we can use scopedProfile
directly, without checking once more.

[Ilya Sherman, 2014/10/29 00:57:12]

My point is: Why does TrackCallback check g_scoped_profile_mode explicitly?  It
seems like it could skip that check.

[vadimt, 2014/10/29 17:47:29]

This allows me to totally skip creating/destroying ScopedProfile in Stable. Even
though it's very optimized, I don't see why we shouldn't use this opportunity,
given that it's technically feasible. We also save on additional invocation of a
callback doe to indirection.

[Ilya Sherman, 2014/10/30 00:51:35]

I think this is unnecessary optimization that reduces readability.  However, if
you're really super attached to it, I don't feel strongly enough to try to
dissuade you.

+  callback.Run();
+}
+
 }  // namespace
 
 // static
@@ -17,6 +26,15 @@ void ScopedTracker::Enable() {
   g_scoped_profile_mode = ScopedProfile::ENABLED;
 }
 
+// static
+base::Closure ScopedTracker::TrackCallback(const Location& location,
+                                           const base::Closure& callback) {
+  if (g_scoped_profile_mode != ScopedProfile::ENABLED)
+    return callback;
+
+  return base::Bind(ExecuteAndAugmentCallback, location, callback);
+}
+
 ScopedTracker::ScopedTracker(const Location& location)
     : scoped_profile_(location, g_scoped_profile_mode) {
 }