Move ResourceHandler deferred actions ahead of external protocol handling.

content/browser/loader/resource_loader.cc

Index: content/browser/loader/resource_loader.cc
diff --git a/content/browser/loader/resource_loader.cc b/content/browser/loader/resource_loader.cc
index bb77021ac8fa20c3d369154da1b6f0adcd0df945..742d8fe999b2fa27cf75225f1aba5298b20d53fe 100644
--- a/content/browser/loader/resource_loader.cc
+++ b/content/browser/loader/resource_loader.cc
@@ -157,11 +157,6 @@ ResourceLoader::~ResourceLoader() {
 }
 
 void ResourceLoader::StartRequest() {
-  if (delegate_->HandleExternalProtocol(this, request_->url())) {
-    CancelAndIgnore();
-    return;
-  }
-
   // Give the handler a chance to delay the URLRequest from being started.
   bool defer_start = false;
   if (!handler_->OnWillStart(request_->url(), &defer_start)) {
@@ -273,12 +268,6 @@ void ResourceLoader::OnReceivedRedirect(net::URLRequest* unused,
     }
   }
 
-  if (delegate_->HandleExternalProtocol(this, redirect_info.new_url)) {
-    // The request is complete so we can remove it.
-    CancelAndIgnore();
-    return;
-  }
-
   scoped_refptr<ResourceResponse> response = new ResourceResponse();
   PopulateResourceResponse(info, request_.get(), response.get());
   delegate_->DidReceiveRedirect(this, redirect_info.new_url, response.get());
@@ -286,6 +275,12 @@ void ResourceLoader::OnReceivedRedirect(net::URLRequest* unused,
     Cancel();
   } else if (*defer) {
     deferred_stage_ = DEFERRED_REDIRECT;  // Follow redirect when resumed.
+    DCHECK(deferred_redirect_url_.is_empty());
+    deferred_redirect_url_ = redirect_info.new_url;
+  } else if (delegate_->HandleExternalProtocol(this, redirect_info.new_url)) {
+    // The request is complete so we can remove it.
+    CancelAndIgnore();
+    return;
   }
 }
 
@@ -450,7 +445,7 @@ void ResourceLoader::Resume() {
       StartRequestInternal();
       break;
     case DEFERRED_REDIRECT:
-      request_->FollowDeferredRedirect();
+      FollowDeferredRedirectInternal();
       break;
     case DEFERRED_READ:
       base::ThreadTaskRunnerHandle::Get()->PostTask(
@@ -476,8 +471,14 @@ void ResourceLoader::Cancel() {
 }
 
 void ResourceLoader::StartRequestInternal() {
+  // At this point any possible deferred start is already over.

[mmenke, 2016/12/16 16:19:36]

I don't understand this comment, or what it has to do with the DCHECK.

[carlosk, 2016/12/20 19:23:31]

It was just meant to clarify that once this method is call all actions (if any)
from a deferred start (if one occurred) are now completed.

Bad positioning above the DCHECK. I moved and rephrased a bit. WDYT?

   DCHECK(!request_->is_pending());
 
+  if (delegate_->HandleExternalProtocol(this, request_->url())) {
+    CancelAndIgnore();
+    return;
+  }
+
   if (!request_->status().is_success()) {

[mmenke, 2016/12/16 16:19:36]

Not quite sure what this is checking (Hrm...), but it should presumably be
before the HandleExternalProtocol call - if something cancelled the request, we
don't want to try to try to handle external protocols.

[carlosk, 2016/12/20 19:23:31]

Done.

It was not the case before my change, but either would deferred actions have
taken place before the HEP call. So I agree it makes sense.

     return;
   }
@@ -534,6 +535,16 @@ void ResourceLoader::CancelRequestInternal(int error, bool from_renderer) {
   }
 }
 
+void ResourceLoader::FollowDeferredRedirectInternal() {
+  DCHECK(!deferred_redirect_url_.is_empty());
+  if (delegate_->HandleExternalProtocol(this, deferred_redirect_url_)) {
+    CancelAndIgnore();
+  } else {
+    request_->FollowDeferredRedirect();
+  }
+  deferred_redirect_url_ = GURL();

[mmenke, 2016/12/16 16:19:36]

Should clear this before calling FollowDeferredRedirect() - it shouldn't matter,
as I don't believe |this| can be deleted, or another redirect seen, before
FollowDeferredRedirect returns, but best to be safe against future refactors.

[carlosk, 2016/12/20 19:23:31]

Done.

+}
+
 void ResourceLoader::CompleteResponseStarted() {
   ResourceRequestInfoImpl* info = GetRequestInfo();
   scoped_refptr<ResourceResponse> response = new ResourceResponse();