No-op changes to relative timeout support code.

PiperOrigin-RevId: 847827629
Change-Id: I84dec0fafa6cdbb8ffee013f9d5ad9b3cb977ee4

Author: derekmauro

absl/synchronization/BUILD.bazel

@@ -72,9 +72,7 @@ cc_library(
         "//absl/base:core_headers",
         "//absl/base:raw_logging_internal",
         "//absl/time",
-    ] + select({
-        "//conditions:default": [],
-    }),
+    ],
 )
 
 cc_test(

absl/synchronization/internal/kernel_timeout.h

@@ -129,8 +129,8 @@ class KernelTimeout {
   std::chrono::nanoseconds ToChronoDuration() const;
 
   // Returns true if steady (aka monotonic) clocks are supported by the system.
-  // This method exists because go/btm requires synchronized clocks, and
-  // thus requires we use the system (aka walltime) clock.
+  // This currently returns true on all platforms, but we have encountered
+  // platforms that once lacked steady clock support.
   static constexpr bool SupportsSteadyClock() { return true; }
 
  private:

absl/synchronization/internal/kernel_timeout_test.cc

@@ -24,12 +24,22 @@
 #include "absl/time/time.h"
 #include "gtest/gtest.h"
 
-// Test go/btm support by randomizing the value of clock_gettime() for
-// CLOCK_MONOTONIC. This works by overriding a weak symbol in glibc.
+#if 0  // All supported platforms currently have steady clocks.
+#define ABSL_INTERNAL_KERNEL_TIMEOUT_SUPPORTS_STEADY_CLOCK 0
+#else
+#define ABSL_INTERNAL_KERNEL_TIMEOUT_SUPPORTS_STEADY_CLOCK 1
+#endif
+
+static_assert(
+    absl::synchronization_internal::KernelTimeout::SupportsSteadyClock() ==
+    static_cast<bool>(ABSL_INTERNAL_KERNEL_TIMEOUT_SUPPORTS_STEADY_CLOCK));
+
+// Randomizing the value of clock_gettime() for CLOCK_MONOTONIC.
+// This works by overriding a weak symbol in glibc.
 // We should be resistant to this randomization when !SupportsSteadyClock().
-#if defined(__GOOGLE_GRTE_VERSION__) &&      \
-    !defined(ABSL_HAVE_ADDRESS_SANITIZER) && \
-    !defined(ABSL_HAVE_MEMORY_SANITIZER) &&  \
+#if !ABSL_INTERNAL_KERNEL_TIMEOUT_SUPPORTS_STEADY_CLOCK && \
+    !defined(ABSL_HAVE_ADDRESS_SANITIZER) &&               \
+    !defined(ABSL_HAVE_MEMORY_SANITIZER) &&                \
     !defined(ABSL_HAVE_THREAD_SANITIZER)
 extern "C" int __clock_gettime(clockid_t c, struct timespec* ts);