Add a test that quantizes MemoryInfo's largest bucket

Bug: 939100
Change-Id: Ia8b7bd430ece375a14569d86482b38c9ad461fb7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1506877Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638680}

third_party/blink/renderer/core/timing/memory_info_test.cc

@@ -54,6 +54,12 @@ TEST(MemoryInfo, quantizeMemorySize) {
   EXPECT_EQ(10000000u, QuantizeMemorySize(3));
   EXPECT_EQ(10000000u, QuantizeMemorySize(1));
   EXPECT_EQ(10000000u, QuantizeMemorySize(0));
+  // Rounding differences between OS's may affect the precise value of the last
+  // bucket.
+  EXPECT_LE(3760000000u,
+            QuantizeMemorySize(std::numeric_limits<size_t>::max()));
+  EXPECT_GT(4000000000u,
+            QuantizeMemorySize(std::numeric_limits<size_t>::max()));
 }
 
 static constexpr int kModForBucketizationCheck = 100000;