ServiceWorker: Add an API to fallback to renderer for CORS preflight

content/browser/service_worker/service_worker_controllee_request_handler.cc

Index: content/browser/service_worker/service_worker_controllee_request_handler.cc
diff --git a/content/browser/service_worker/service_worker_controllee_request_handler.cc b/content/browser/service_worker/service_worker_controllee_request_handler.cc
index e45ca4c7d3f425d276d0c548aa33c3be1e74b974..9bf56fd1fd1f37d1e848cdb5154dbd82753c1261 100644
--- a/content/browser/service_worker/service_worker_controllee_request_handler.cc
+++ b/content/browser/service_worker/service_worker_controllee_request_handler.cc
@@ -285,7 +285,7 @@ void ServiceWorkerControlleeRequestHandler::OnVersionStatusChanged(
   if (version != registration->active_version() ||
       version->status() != ServiceWorkerVersion::ACTIVATED ||
       !provider_host_) {
-    job_->FallbackToNetwork();
+    job_->FallbackToNetworkOrRenderer();

[falken, 2016/07/07 01:11:12]

Sorry I no longer understand this. We only get here from
DidLookupRegistrationForMainResource only, which means job_ is for a main
resource request. So FallbackToNetworkOrRenderer would always FallbackToNetwork,
no?

Same for the call sites below.

[shimazu, 2016/07/07 05:02:32]

Ah, yes, it seems correct. Actually I'd like to use FallbackToNetworkOrRenderer
at the next patch:  http://crrev.com/2103063002.
Fixed.

     return;
   }
 
@@ -309,7 +309,7 @@ void ServiceWorkerControlleeRequestHandler::DidUpdateRegistration(
     return;
 
   if (!context_) {
-    job_->FallbackToNetwork();
+    job_->FallbackToNetworkOrRenderer();
     return;
   }
   if (status != SERVICE_WORKER_OK ||
@@ -342,7 +342,7 @@ void ServiceWorkerControlleeRequestHandler::OnUpdatedVersionStatusChanged(
     return;
 
   if (!context_) {
-    job_->FallbackToNetwork();
+    job_->FallbackToNetworkOrRenderer();
     return;
   }
   if (version->status() == ServiceWorkerVersion::ACTIVATED ||