service worker: Stop serializing storage operations

To de-flake payment related browser_tests.

These tests call GetUserDataForAllRegistrationsByKeyPrefix() more than
500 times. Storage operations are serialized as of
crrev.com/c/2494208 but the serialization mechanism doesn't seem to be
working correctly for these tests. There seems a situation where we
don't call the callback of the method and hit DCHECK() in mojo generated
bindings.

This CL stops serializing storage operations. Follow-up CLs will address
the root cause and re-implement the serialization.

I ran LoadAndRemoveIframeWithManyPaymentRequestsTest 50 times on my
local environment and didn't observe flakiness. Without this CL the
test crashed once every 5 times.

Bug: 1129578,1133143
Change-Id: I3054f02eadfb21c570124aca5a377d8112ef8cea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2584432
Auto-Submit: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836541}

content/browser/service_worker/service_worker_context_core_unittest.cc

@@ -312,7 +312,7 @@ TEST_F(ServiceWorkerContextCoreTest, DeleteForOrigin_UnregisterFail) {
   loop.Run();
 
   // The operation should still complete.
-  EXPECT_EQ(blink::ServiceWorkerStatusCode::kErrorAbort, status);
+  EXPECT_EQ(blink::ServiceWorkerStatusCode::kErrorFailed, status);
 }
 
 }  // namespace content

content/browser/service_worker/service_worker_registry.cc

@@ -1616,8 +1616,8 @@ void ServiceWorkerRegistry::DidRecover() {
   connection_state_ = ConnectionState::kNormal;
 
   // Retry inflight calls.
-  if (inflight_calls_.size() > 0)
-    inflight_calls_.begin()->second->Run(this);
+  for (auto& call : inflight_calls_)
+    call.second->Run(this);
 }
 
 uint64_t ServiceWorkerRegistry::GetNextCallId() {
@@ -1629,19 +1629,14 @@ void ServiceWorkerRegistry::StartRemoteCall(
     std::unique_ptr<InflightCall> call) {
   DCHECK(!base::Contains(inflight_calls_, call_id));
   inflight_calls_[call_id] = std::move(call);
-  if (connection_state_ == ConnectionState::kNormal &&
-      inflight_calls_.size() == 1) {
-    // There are no inflight calls. Start the current one.
-    inflight_calls_.begin()->second->Run(this);
+  if (connection_state_ == ConnectionState::kNormal) {
+    inflight_calls_[call_id]->Run(this);
   }
 }
 
 void ServiceWorkerRegistry::FinishRemoteCall(uint64_t call_id) {
   DCHECK(base::Contains(inflight_calls_, call_id));
   inflight_calls_.erase(call_id);
-  // Start the next call if any.
-  if (inflight_calls_.size() > 0)
-    inflight_calls_.begin()->second->Run(this);
 }
 
 template <typename T>