Increase Chi-square limit in ASR tests

Previously ASR tests were asserting that Chi-square value for each bit
were below 24.0. On 64-bit platforms that condition is tested about
19000 times, so probability that at least one test fails was about 2%.
Increased the limit to 35.

Bug: 811881
Change-Id: Ia192ccf62abdd125053a0d005e632d55e8374538
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1642109
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665991}

base/allocator/partition_allocator/address_space_randomization_unittest.cc

@@ -180,9 +180,10 @@ void RandomBitCorrelation(int random_bit) {
       // Chi squared analysis for k = 2 (2, states: same/not-same) and one
       // degree of freedom (k - 1).
       double chi_squared = ChiSquared(m, kRepeats);
-      // For 1 degree of freedom this corresponds to 1 in a million.  We are
-      // running ~8000 tests, so that would be surprising.
-      CHECK_GE(24, chi_squared);
+      // For k=2 probability of Chi^2 < 35 is p=3.338e-9. This condition is
+      // tested ~19000 times, so probability of it failing randomly per one
+      // base_unittests run is (1 - (1 - p) ^ 19000) ~= 6e-5.
+      CHECK_LE(chi_squared, 35.0);
       // If the predictor bit is a fixed 0 or 1 then it makes no sense to
       // repeat the test with a different age.
       if (predictor_bit < 0)
@@ -191,9 +192,6 @@ void RandomBitCorrelation(int random_bit) {
   }
 }
 
-// TODO(crbug.com/811881): These are flaky on Fuchsia
-#if !defined(OS_FUCHSIA)
-
 // Tests are fairly slow, so give each random bit its own test.
 #define TEST_RANDOM_BIT(BIT)                                        \
   TEST(AddressSpaceRandomizationTest, RandomBitCorrelations##BIT) { \
@@ -242,8 +240,6 @@ TEST_RANDOM_BIT(48)
 // No platforms have more than 48 address bits.
 #endif  // defined(ARCH_CPU_64_BITS)
 
-#endif  // defined(OS_FUCHSIA)
-
 #undef TEST_RANDOM_BIT
 
 }  // namespace base