Ensure the scheduler always changes from UseCase LOADING to NONE.

third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetector.cpp

Index: third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetector.cpp
diff --git a/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetector.cpp b/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetector.cpp
index 5b75deca1ecaa2adbd3f5da0cf28d46e95bae8de..34ab1db5ed5de7ecf31e483898b2558cdd30c748 100644
--- a/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetector.cpp
+++ b/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetector.cpp
@@ -113,7 +113,8 @@ void FirstMeaningfulPaintDetector::notifyPaint() {
     m_seenFirstMeaningfulPaintCandidate = true;
     return;
   }
-  m_paintTiming->markFirstMeaningfulPaintCandidate();
+  m_paintTiming->setFirstMeaningfulPaintCandidate(
+      m_provisionalFirstMeaningfulPaint);
 }
 
 int FirstMeaningfulPaintDetector::activeConnections() {
@@ -170,6 +171,11 @@ void FirstMeaningfulPaintDetector::network2QuietTimerFired(TimerBase*) {
   m_network2QuietReached = true;
 
   if (m_provisionalFirstMeaningfulPaint) {
+    // If there's only been one contentful paint, then there won't have been
+    // a meaningful paint signalled to the Scheduler, so mark one now.
+    // This is a no-op if a FMPC has already been marked.
+    m_paintTiming->setFirstMeaningfulPaintCandidate(
+        m_provisionalFirstMeaningfulPaint);
     // Enforce FirstContentfulPaint <= FirstMeaningfulPaint.
     m_firstMeaningfulPaint2Quiet =
         std::max(m_provisionalFirstMeaningfulPaint,