Revert of [Chromecast][Temporary] Disable TCMallocTest.Realloc on cast audio.

chromecast/BUILD.gn

Index: chromecast/BUILD.gn
diff --git a/chromecast/BUILD.gn b/chromecast/BUILD.gn
index ac1d8efe5945b5ed4311a3785b1562586c292a09..aff41843d8257d3ffe29354e6619aa291c63b130 100644
--- a/chromecast/BUILD.gn
+++ b/chromecast/BUILD.gn
@@ -149,13 +149,6 @@
         # Also disable TimeFormattingTest on audio-only builds, since we don't
         # include the necessary info in icudtl.dat.
         gtest_excludes += [ "TimeFormattingTest.*" ]
-
-        # TODO(mbjorge): Temporarily disable Realloc test on audio devices,
-        # since it mysteriously is failing. As part of an effort to re-green
-        # the unittests, current (2017-03-15) failures are being disabled to get
-        # back to a green state. Re-enable once the tests have been fixed.
-        # b/36238217, hotlist/461351
-        gtest_excludes += [ "TCMallocTest.Realloc" ]
       }
     }
   }