Revert of Remove unused blocking pool methods from web::WebThread.

ios/web/web_thread_impl.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ios/web/web_thread_impl.h"
 
 #include <string>
 #include <utility>
 
 #include "base/atomicops.h"
@@ skipping 312 matching lines @@
     }
   }
 
   if (!target_thread_outlives_current)
     globals.lock.Release();
 
   return !!message_loop;
 }
 
 // static
+bool WebThread::PostBlockingPoolTask(const tracked_objects::Location& from_here,
+                                     base::OnceClosure task) {
+  return g_globals.Get().blocking_pool->PostWorkerTask(from_here,
+                                                       std::move(task));
+}
+
+// static
+bool WebThread::PostBlockingPoolTaskAndReply(
+    const tracked_objects::Location& from_here,
+    base::OnceClosure task,
+    base::OnceClosure reply) {
+  return g_globals.Get().blocking_pool->PostTaskAndReply(
+      from_here, std::move(task), std::move(reply));
+}
+
+// static
+bool WebThread::PostBlockingPoolSequencedTask(
+    const std::string& sequence_token_name,
+    const tracked_objects::Location& from_here,
+    base::OnceClosure task) {
+  return g_globals.Get().blocking_pool->PostNamedSequencedWorkerTask(
+      sequence_token_name, from_here, std::move(task));
+}
+
+// static
 base::SequencedWorkerPool* WebThread::GetBlockingPool() {
   return g_globals.Get().blocking_pool.get();
 }
 
 // static
 bool WebThread::IsThreadInitialized(ID identifier) {
   if (g_globals == nullptr)
     return false;
 
   WebThreadGlobals& globals = g_globals.Get();
@@ skipping 113 matching lines @@
   AtomicWord* storage =
       reinterpret_cast<AtomicWord*>(&globals.thread_delegates[identifier]);
   AtomicWord old_pointer = base::subtle::NoBarrier_AtomicExchange(
       storage, reinterpret_cast<AtomicWord>(delegate));
 
   // This catches registration when previously registered.
   DCHECK(!delegate || !old_pointer);
 }
 
 }  // namespace web