Remove `grpc_core::WaitUntilWith{Deadline,Timeout}` (#26867)

These functions are essentially unused.

src/core/lib/gprpp/sync.h

@@ -19,10 +19,9 @@
 #ifndef GRPC_CORE_LIB_GPRPP_SYNC_H
 #define GRPC_CORE_LIB_GPRPP_SYNC_H
 
-#include <grpc/impl/codegen/port_platform.h>
+#include <grpc/support/port_platform.h>
 
-#include <grpc/impl/codegen/log.h>
-#include <grpc/impl/codegen/sync.h>
+#include <grpc/support/log.h>
 #include <grpc/support/sync.h>
 #include <grpc/support/time.h>
 
@@ -152,26 +151,6 @@ static void WaitUntil(CondVar* cv, Mutex* mu, Predicate pred) {
   }
 }
 
-// Returns true iff we timed-out
-template <typename Predicate>
-static bool WaitUntilWithTimeout(CondVar* cv, Mutex* mu, Predicate pred,
-                                 absl::Duration timeout) {
-  while (!pred()) {
-    if (cv->WaitWithTimeout(mu, timeout)) return true;
-  }
-  return false;
-}
-
-// Returns true iff we timed-out
-template <typename Predicate>
-static bool WaitUntilWithDeadline(CondVar* cv, Mutex* mu, Predicate pred,
-                                  absl::Time deadline) {
-  while (!pred()) {
-    if (cv->WaitWithDeadline(mu, deadline)) return true;
-  }
-  return false;
-}
-
 // Deprecated. Prefer MutexLock
 class MutexLockForGprMu {
  public:

test/cpp/end2end/xds_end2end_test.cc

@@ -792,20 +792,17 @@ class AdsServiceImpl : public std::enable_shared_from_this<AdsServiceImpl> {
                   response->DebugString().c_str());
           stream->Write(response.value());
         }
-        // If we didn't find anything to do, delay before the next loop
-        // iteration; otherwise, check whether we should exit and then
-        // immediately continue.
-        gpr_timespec deadline =
-            grpc_timeout_milliseconds_to_deadline(did_work ? 0 : 10);
         {
           grpc_core::MutexLock lock(&parent_->ads_mu_);
-          if (!grpc_core::WaitUntilWithDeadline(
-                  &parent_->ads_cond_, &parent_->ads_mu_,
-                  [this] { return parent_->ads_done_; },
-                  grpc_core::ToAbslTime(deadline))) {
+          if (parent_->ads_done_) {
             break;
           }
         }
+        // If we didn't find anything to do, delay before the next loop
+        // iteration; otherwise, check whether we should exit and then
+        // immediately continue.
+        gpr_sleep_until(
+            grpc_timeout_milliseconds_to_deadline(did_work ? 0 : 10));
       }
       // Done with main loop.  Clean up before returning.
       // Join reader thread.