From dd7c87fd1f04bfe296ecc194a35e4c7eea52daeb Mon Sep 17 00:00:00 2001
From: Dragana Damjanovic <dd.mozilla@gmail.com>
Date: Tue, 30 Oct 2018 10:27:28 +0000
Subject: [PATCH] Bug 1503011 - Make sure DNSPrefetch is called. r=mayhemer

Differential Revision: https://phabricator.services.mozilla.com/D10118

--HG--
extra : moz-landing-system : lando
---
 netwerk/protocol/http/nsHttpChannel.cpp | 37 +++++++++++++++----------
 netwerk/protocol/http/nsHttpChannel.h   |  1 +
 2 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/netwerk/protocol/http/nsHttpChannel.cpp b/netwerk/protocol/http/nsHttpChannel.cpp
index 9a721d8eb059..08cb0ecd1c64 100644
--- a/netwerk/protocol/http/nsHttpChannel.cpp
+++ b/netwerk/protocol/http/nsHttpChannel.cpp
@@ -6687,6 +6687,7 @@ nsHttpChannel::BeginConnect()
     }
 
     if (!(mLoadFlags & LOAD_CLASSIFY_URI)) {
+        MaybeStartDNSPrefetch();
         return ContinueBeginConnectWithResult();
     }
 
@@ -6721,21 +6722,9 @@ nsHttpChannel::BeginConnect()
     return NS_OK;
 }
 
-nsresult
-nsHttpChannel::BeginConnectActual()
+void
+nsHttpChannel::MaybeStartDNSPrefetch()
 {
-    if (mCanceled) {
-        return mStatus;
-    }
-
-    if (mTrackingProtectionCancellationPending) {
-        LOG(("Waiting for tracking protection cancellation in BeginConnectActual [this=%p]\n", this));
-        MOZ_ASSERT(!mCallOnResume ||
-                   mCallOnResume == &nsHttpChannel::HandleContinueCancelledByTrackingProtection,
-                   "We should be paused waiting for cancellation from tracking protection");
-        return NS_OK;
-    }
-
     if (!mConnectionInfo->UsingHttpProxy() &&
         !(mLoadFlags & (LOAD_NO_NETWORK_IO | LOAD_ONLY_FROM_CACHE))) {
         // Start a DNS lookup very early in case the real open is queued the DNS can
@@ -6751,7 +6740,7 @@ nsHttpChannel::BeginConnectActual()
         // be correct, and even when it isn't, the timing still represents _a_
         // valid DNS lookup timing for the site, even if it is not _the_
         // timing we used.
-        LOG(("nsHttpChannel::BeginConnect [this=%p] prefetching%s\n",
+        LOG(("nsHttpChannel::MaybeStartDNSPrefetch [this=%p] prefetching%s\n",
              this, mCaps & NS_HTTP_REFRESH_DNS ? ", refresh requested" : ""));
         OriginAttributes originAttributes;
         NS_GetOriginAttributes(this, originAttributes);
@@ -6759,6 +6748,24 @@ nsHttpChannel::BeginConnectActual()
                                          this, mTimingEnabled);
         mDNSPrefetch->PrefetchHigh(mCaps & NS_HTTP_REFRESH_DNS);
     }
+}
+
+nsresult
+nsHttpChannel::BeginConnectActual()
+{
+    if (mCanceled) {
+        return mStatus;
+    }
+
+    if (mTrackingProtectionCancellationPending) {
+        LOG(("Waiting for tracking protection cancellation in BeginConnectActual [this=%p]\n", this));
+        MOZ_ASSERT(!mCallOnResume ||
+                   mCallOnResume == &nsHttpChannel::HandleContinueCancelledByTrackingProtection,
+                   "We should be paused waiting for cancellation from tracking protection");
+        return NS_OK;
+    }
+
+    MaybeStartDNSPrefetch();
 
     nsresult rv = ContinueBeginConnectWithResult();
     if (NS_FAILED(rv)) {
diff --git a/netwerk/protocol/http/nsHttpChannel.h b/netwerk/protocol/http/nsHttpChannel.h
index ba8198a26a4a..f4c12e8c632a 100644
--- a/netwerk/protocol/http/nsHttpChannel.h
+++ b/netwerk/protocol/http/nsHttpChannel.h
@@ -300,6 +300,7 @@ private:
     // Connections will only be established in this function.
     // (including DNS prefetch and speculative connection.)
     nsresult BeginConnectActual();
+    void MaybeStartDNSPrefetch();
 
     // We might synchronously or asynchronously call BeginConnectActual,
     // which includes DNS prefetch and speculative connection, according to