diff --git a/net/disk_cache/simple/simple_index.cc b/net/disk_cache/simple/simple_index.cc
index f2438af8debd31..c41c829bdefd80 100644
--- a/net/disk_cache/simple/simple_index.cc
+++ b/net/disk_cache/simple/simple_index.cc
@@ -140,7 +140,7 @@ SimpleIndex::SimpleIndex(
       app_on_background_(false) {}
 
 SimpleIndex::~SimpleIndex() {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
 
   // Fail all callbacks waiting for the index to come up.
   for (CallbackList::iterator it = to_run_when_initialized_.begin(),
@@ -150,7 +150,7 @@ SimpleIndex::~SimpleIndex() {
 }
 
 void SimpleIndex::Initialize(base::Time cache_mtime) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
 
 #if defined(OS_ANDROID)
   if (base::android::IsVMInitialized()) {
@@ -178,7 +178,7 @@ void SimpleIndex::SetMaxSize(uint64_t max_bytes) {
 }
 
 int SimpleIndex::ExecuteWhenReady(const net::CompletionCallback& task) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
   if (initialized_)
     io_thread_->PostTask(FROM_HERE, base::Bind(task, net::OK));
   else
@@ -251,7 +251,7 @@ size_t SimpleIndex::EstimateMemoryUsage() const {
 }
 
 void SimpleIndex::Insert(uint64_t entry_hash) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
   // Upon insert we don't know yet the size of the entry.
   // It will be updated later when the SimpleEntryImpl finishes opening or
   // creating the new entry, and then UpdateEntrySize will be called.
@@ -263,7 +263,7 @@ void SimpleIndex::Insert(uint64_t entry_hash) {
 }
 
 void SimpleIndex::Remove(uint64_t entry_hash) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
   EntrySet::iterator it = entries_set_.find(entry_hash);
   if (it != entries_set_.end()) {
     UpdateEntryIteratorSize(&it, 0u);
@@ -282,7 +282,7 @@ bool SimpleIndex::Has(uint64_t hash) const {
 }
 
 bool SimpleIndex::UseIfExists(uint64_t entry_hash) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
   // Always update the last used time, even if it is during initialization.
   // It will be merged later.
   EntrySet::iterator it = entries_set_.find(entry_hash);
@@ -295,7 +295,7 @@ bool SimpleIndex::UseIfExists(uint64_t entry_hash) {
 }
 
 void SimpleIndex::StartEvictionIfNeeded() {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
   if (eviction_in_progress_ || cache_size_ <= high_watermark_)
     return;
   // Take all live key hashes from the index and sort them by time.
@@ -352,7 +352,7 @@ void SimpleIndex::StartEvictionIfNeeded() {
 
 bool SimpleIndex::UpdateEntrySize(uint64_t entry_hash,
                                   base::StrictNumeric<uint32_t> entry_size) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
   EntrySet::iterator it = entries_set_.find(entry_hash);
   if (it == entries_set_.end())
     return false;
@@ -364,7 +364,7 @@ bool SimpleIndex::UpdateEntrySize(uint64_t entry_hash,
 }
 
 void SimpleIndex::EvictionDone(int result) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
 
   // Ignore the result of eviction. We did our best.
   eviction_in_progress_ = false;
@@ -416,7 +416,7 @@ void SimpleIndex::UpdateEntryIteratorSize(
 
 void SimpleIndex::MergeInitializingSet(
     std::unique_ptr<SimpleIndexLoadResult> load_result) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
   DCHECK(load_result->did_load);
 
   EntrySet* index_file_entries = &load_result->entries;
@@ -482,7 +482,7 @@ void SimpleIndex::MergeInitializingSet(
 #if defined(OS_ANDROID)
 void SimpleIndex::OnApplicationStateChange(
     base::android::ApplicationState state) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
   // For more info about android activities, see:
   // developer.android.com/training/basics/activity-lifecycle/pausing.html
   if (state == base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES) {
@@ -496,7 +496,7 @@ void SimpleIndex::OnApplicationStateChange(
 #endif
 
 void SimpleIndex::WriteToDisk(IndexWriteToDiskReason reason) {
-  CHECK(io_thread_checker_.CalledOnValidThread());
+  DCHECK(io_thread_checker_.CalledOnValidThread());
   if (!initialized_)
     return;
   SIMPLE_CACHE_UMA(CUSTOM_COUNTS,
diff --git a/net/disk_cache/simple/simple_index.h b/net/disk_cache/simple/simple_index.h
index 3877f1e2a85fa6..6740c2c91e2b81 100644
--- a/net/disk_cache/simple/simple_index.h
+++ b/net/disk_cache/simple/simple_index.h
@@ -230,9 +230,7 @@ class NET_EXPORT_PRIVATE SimpleIndex
 
   // All nonstatic SimpleEntryImpl methods should always be called on the IO
   // thread, in all cases. |io_thread_checker_| documents and enforces this.
-  // NOTE: Temporarily forced on to chase a crash, https://crbug.com/710994,
-  // turn off by 2017-04-21, also going back CHECK -> DCHECK in the impl.
-  base::ThreadCheckerImpl io_thread_checker_;
+  base::ThreadChecker io_thread_checker_;
 
   // Timestamp of the last time we wrote the index to disk.
   // PostponeWritingToDisk() may give up postponing and allow the write if it