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 b5ee403534cec10fc0bbb2e4f38c184cdfc8bab9..c46186643984f90df6ab0cd44d4dfd50b6a2fd85 100644
--- a/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp
+++ b/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp
@@ -107,6 +107,24 @@ TEST_F(FirstMeaningfulPaintDetectorTest, FirstMeaningfulPaintCandidate) {
 }
 
 TEST_F(FirstMeaningfulPaintDetectorTest,
+       OnlyOneFirstMeaningfulPaintCandidateBeforeNetworkStable) {
+  paintTiming().markFirstContentfulPaint();
+  EXPECT_EQ(paintTiming().firstMeaningfulPaintCandidate(), 0.0);
+  simulateLayoutAndPaint(1);
+  // The first candidate gets ignored.
+  EXPECT_EQ(paintTiming().firstMeaningfulPaintCandidate(), 0.0);
+  double afterPaint = monotonicallyIncreasingTime();
+  simulateNetworkStable();
+  // The networkStable even creates a FMP candidate.
+  EXPECT_GT(paintTiming().firstMeaningfulPaintCandidate(), afterPaint);
+  double candidate = paintTiming().firstMeaningfulPaintCandidate();
+  // The second candidate gets ignored since "networkStable" created the second
+  // candidate.
+  simulateLayoutAndPaint(10);
+  EXPECT_EQ(paintTiming().firstMeaningfulPaintCandidate(), candidate);
+}
+
+TEST_F(FirstMeaningfulPaintDetectorTest,
        NetworkStableBeforeFirstContentfulPaint) {
   paintTiming().markFirstPaint();
   simulateLayoutAndPaint(1);