[FCP++] Fix test flakiness due to time clamping

The test LastTextPaint_ReportFirstPaintTime is flaky because it used
EXPECT_GT for time comparison. This is an issue because time is clamped. We
should use EXPECT_GE instead.

Bug: 885123
Change-Id: I519eeb23dcd9a1376cf91ecdc288fbf6d7b40daa
Reviewed-on: https://chromium-review.googlesource.com/1230436Reviewed-by: Steve Kobes <skobes@chromium.org>
Commit-Queue: Liquan (Max) Gǔ <maxlg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592073}

third_party/blink/renderer/core/paint/text_paint_timing_detector_test.cc

@@ -97,8 +97,8 @@ TEST_F(TextPaintTimingDetectorTest, LargestTextPaint_ReportFirstPaintTime) {
                            .FindLargestPaintCandidate();
   EXPECT_EQ(record->text, "a long-long-long-long moving text");
   TimeTicks firing_time = record->first_paint_time;
-  EXPECT_GT(firing_time, time1);
-  EXPECT_GT(time2, firing_time);
+  EXPECT_GE(firing_time, time1);
+  EXPECT_GE(time2, firing_time);
 }
 
 TEST_F(TextPaintTimingDetectorTest,
@@ -238,8 +238,8 @@ TEST_F(TextPaintTimingDetectorTest, LastTextPaint_ReportFirstPaintTime) {
       GetPaintTracker().GetTextPaintTimingDetector().FindLastPaintCandidate();
   EXPECT_EQ(record->text, "latest text");
   TimeTicks firing_time = record->first_paint_time;
-  EXPECT_GT(firing_time, time1);
-  EXPECT_GT(time2, firing_time);
+  EXPECT_GE(firing_time, time1);
+  EXPECT_GE(time2, firing_time);
 }
 
 TEST_F(TextPaintTimingDetectorTest, LastTextPaint_IgnoreRemovedText) {