Revert 213906 "base: Re-apply WeakPtr support for SequencedWorke..."

Speculative due to base_unittests failures.

> base: Re-apply WeakPtr support for SequencedWorkerPools, fixing deadlock
> 
> This reverts the revert found here: https://codereview.chromium.org/19882002
> 
> It also fixes the deadlock that caused the revert, reported here:
> http://crbug.com/261448
> 
> Patchset 1 is simply what was originally committed (and reverted). Subsequent patchsets show the fix of the deadlock problem.
> 
> BUG=165590
> TBR=darin
> 
> Review URL: https://chromiumcodereview.appspot.com/20163004

TBR=tommycli@chromium.org

Review URL: https://codereview.chromium.org/20771002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@213943 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 12 insertions, 27 deletions

diff --git a/base/sequence_checker_impl.cc b/base/sequence_checker_impl.cc
index e95b8ee..24d9ed9 100644
--- a/base/sequence_checker_impl.cc
+++ b/base/sequence_checker_impl.cc
@@ -4,43 +4,28 @@
 
 #include "base/sequence_checker_impl.h"
 
+#include "base/sequenced_task_runner.h"
+
 namespace base {
 
-SequenceCheckerImpl::SequenceCheckerImpl()
-    : sequence_token_assigned_(false) {
-  AutoLock auto_lock(lock_);
-  EnsureSequenceTokenAssigned();
-}
+SequenceCheckerImpl::SequenceCheckerImpl(
+    const scoped_refptr<SequencedTaskRunner>& sequenced_task_runner)
+    : sequenced_task_runner_(sequenced_task_runner) {}
 
 SequenceCheckerImpl::~SequenceCheckerImpl() {}
 
-bool SequenceCheckerImpl::CalledOnValidSequencedThread() const {
+bool SequenceCheckerImpl::CalledOnValidSequence() const {
   AutoLock auto_lock(lock_);
-  EnsureSequenceTokenAssigned();
-
-  // If this thread is not associated with a SequencedWorkerPool,
-  // SequenceChecker behaves as a ThreadChecker. See header for details.
-  if (!sequence_token_.IsValid())
-    return thread_checker_.CalledOnValidThread();
-
-  return sequence_token_.Equals(
-      SequencedWorkerPool::GetSequenceTokenForCurrentThread());
+  return sequenced_task_runner_.get() ?
+      sequenced_task_runner_->RunsTasksOnCurrentThread() :
+      thread_checker_.CalledOnValidThread();
 }
 
-void SequenceCheckerImpl::DetachFromSequence() {
+void SequenceCheckerImpl::ChangeSequence(
+    const scoped_refptr<SequencedTaskRunner>& sequenced_task_runner) {
   AutoLock auto_lock(lock_);
+  sequenced_task_runner_ = sequenced_task_runner;
   thread_checker_.DetachFromThread();
-  sequence_token_assigned_ = false;
-  sequence_token_ = SequencedWorkerPool::SequenceToken();
-}
-
-void SequenceCheckerImpl::EnsureSequenceTokenAssigned() const {
-  lock_.AssertAcquired();
-  if (sequence_token_assigned_)
-    return;
-
-  sequence_token_assigned_ = true;
-  sequence_token_ = SequencedWorkerPool::GetSequenceTokenForCurrentThread();
 }
 
 }  // namespace base