De-flake property sequence number unit test.

third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositorTest.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/graphics/compositing/PaintArtifactCompositor.h"
 
 #include <memory>
 
 #include "base/test/test_simple_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 1773 matching lines @@
       .rectDrawing(FloatRect(0, 0, 100, 100), Color::white);
   artifact
       .chunk(TransformPaintPropertyNode::root(), ClipPaintPropertyNode::root(),
              EffectPaintPropertyNode::root())
       .rectDrawing(FloatRect(0, 0, 100, 100), Color::gray);
   update(artifact.build());
 
   // Two content layers for the differentiated rect drawings and three dummy
   // layers for each of the transform, clip and effect nodes.
   EXPECT_EQ(5u, rootLayer()->children().size());
-  EXPECT_EQ(1, propertyTrees().sequence_number);
+  int sequenceNumber = propertyTrees().sequence_number;
+  EXPECT_GT(sequenceNumber, 0);
   for (auto layer : rootLayer()->children()) {
-    EXPECT_EQ(1, layer->property_tree_sequence_number());
+    EXPECT_EQ(sequenceNumber, layer->property_tree_sequence_number());
   }
 
   update(artifact.build());
 
   EXPECT_EQ(5u, rootLayer()->children().size());
-  EXPECT_EQ(2, propertyTrees().sequence_number);
+  sequenceNumber++;
+  EXPECT_EQ(sequenceNumber, propertyTrees().sequence_number);
   for (auto layer : rootLayer()->children()) {
-    EXPECT_EQ(2, layer->property_tree_sequence_number());
+    EXPECT_EQ(sequenceNumber, layer->property_tree_sequence_number());
   }
 
   update(artifact.build());
 
   EXPECT_EQ(5u, rootLayer()->children().size());
-  EXPECT_EQ(3, propertyTrees().sequence_number);
+  sequenceNumber++;
+  EXPECT_EQ(sequenceNumber, propertyTrees().sequence_number);
   for (auto layer : rootLayer()->children()) {
-    EXPECT_EQ(3, layer->property_tree_sequence_number());
+    EXPECT_EQ(sequenceNumber, layer->property_tree_sequence_number());
   }
 }
 
 }  // namespace blink