Adding instrumentation to locate the source of jankiness.

Mechanical change that adds instrumentation required to locate the source of
jankiness (i.e. a long-running fragment of code executed as a part of the task
that causes jank) in the code. See the bug for details on what kind of jank we
are after.  A number of similar CLs were landed, and none of them caused issues.
The code of the instrumentation is highly optimized and is not expected to
affect performance. The code simply creates a diagnostic task which is identical
to ones created by PostTask or IPC message handlers.

BUG=455884,455942,455952
TEST=none
TBR=mmenke,michaeln,zea

Review URL: https://codereview.chromium.org/900793009

Cr-Commit-Position: refs/heads/master@{#314970}

1 files changed, 5 insertions, 0 deletions

diff --git a/google_apis/gcm/engine/connection_factory_impl.cc b/google_apis/gcm/engine/connection_factory_impl.cc
index 218f833..a8ec37f 100644
--- a/google_apis/gcm/engine/connection_factory_impl.cc
+++ b/google_apis/gcm/engine/connection_factory_impl.cc
@@ -7,6 +7,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
+#include "base/profiler/scoped_tracker.h"
 #include "google_apis/gcm/engine/connection_handler_impl.h"
 #include "google_apis/gcm/monitoring/gcm_stats_recorder.h"
 #include "google_apis/gcm/protocol/mcs.pb.h"
@@ -342,6 +343,10 @@ base::TimeTicks ConnectionFactoryImpl::NowTicks() {
 }
 
 void ConnectionFactoryImpl::OnConnectDone(int result) {
+  // TODO(pkasting): Remove ScopedTracker below once crbug.com/455884 is fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "455884 ConnectionFactoryImpl::OnConnectDone"));
   if (result != net::OK) {
     // If the connection fails, try another proxy.
     result = ReconsiderProxyAfterError(result);