Add NavigationToFirstContentfulPaint UMA for ServiceWorker controlled pages.

third_party/WebKit/Source/core/loader/FrameLoader.cpp

Index: third_party/WebKit/Source/core/loader/FrameLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameLoader.cpp b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
index ac22f9bc834e354e7d98f385695be53eead44a73..92c031d9cd386b17f850896c6efe6cc2ed6d6a22 100644
--- a/third_party/WebKit/Source/core/loader/FrameLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
@@ -429,6 +429,9 @@ void FrameLoader::receivedFirstData()
 
     client()->dispatchDidCommitLoad(m_currentItem.get(), historyCommitType);
 
+    if (client()->isControlledByServiceWorker(*m_documentLoader))

[Bryan McQuade, 2016/04/14 15:10:26]

i guess it's somewhat subtle, but this has to happen after commit in order for
our metrics tracking logic to handle it properly. looks like you've got that
covered but just want to make sure you are aware.

[horo, 2016/04/14 15:46:31]

Added comment.

+        client()->didObserveLoadingBehavior(WebLoadingBehaviorServiceWorkerControlled);
+
     TRACE_EVENT1("devtools.timeline", "CommitLoad", "data", InspectorCommitLoadEvent::data(m_frame));
     InspectorInstrumentation::didCommitLoad(m_frame, m_documentLoader.get());
     m_frame->page()->didCommitLoad(m_frame);