Ensure the scheduler always changes from UseCase LOADING to NONE.

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

Index: third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp
diff --git a/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp b/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp
index 492362275fb51ef3b2822c301e5ee7ba6512793e..63527abd6e59752c1e253ad66720e9512081ed07 100644
--- a/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp
+++ b/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp
@@ -158,6 +158,23 @@ TEST_F(FirstMeaningfulPaintDetectorTest, FirstMeaningfulPaintCandidate) {
 }
 
 TEST_F(FirstMeaningfulPaintDetectorTest,
+       OnlyOneFirstMeaningfulPaintCandidateBeforeNetworkStable) {
+  paintTiming().markFirstContentfulPaint();
+  EXPECT_EQ(paintTiming().firstMeaningfulPaintCandidate(), 0.0);
+  double beforePaint = monotonicallyIncreasingTime();
+  simulateLayoutAndPaint(1);
+  // The first candidate is initially ignored.
+  EXPECT_EQ(paintTiming().firstMeaningfulPaintCandidate(), 0.0);
+  simulateNetworkStable();
+  // The networkStable then promotes the first candidate.
+  EXPECT_GT(paintTiming().firstMeaningfulPaintCandidate(), beforePaint);
+  double candidate = paintTiming().firstMeaningfulPaintCandidate();
+  // The second candidate is then ignored.
+  simulateLayoutAndPaint(10);
+  EXPECT_EQ(paintTiming().firstMeaningfulPaintCandidate(), candidate);
+}
+
+TEST_F(FirstMeaningfulPaintDetectorTest,
        NetworkStableBeforeFirstContentfulPaint) {
   paintTiming().markFirstPaint();
   simulateLayoutAndPaint(1);