Allow navigations to frames that aren't being unloaded in the unload handler.

third_party/WebKit/Source/core/loader/FrameLoader.cpp

Index: third_party/WebKit/Source/core/loader/FrameLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameLoader.cpp b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
index e330262b19fb0eb8426a68b995ee40a55ccb690f..7d197e71ffa81e5d2db1a4f695de9c2f29d0d9b1 100644
--- a/third_party/WebKit/Source/core/loader/FrameLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
@@ -288,7 +288,7 @@ void FrameLoader::saveScrollState() {
 }
 
 void FrameLoader::dispatchUnloadEvent() {
-  NavigationDisablerForUnload navigationDisabler;
+  FrameNavigationDisabler navigationDisabler(*m_frame);
 
   // If the frame is unloading, the provisional loader should no longer be
   // protected. It will be detached soon.
@@ -1093,7 +1093,7 @@ void FrameLoader::load(const FrameLoadRequest& passedRequest,
                        HistoryLoadType historyLoadType) {
   DCHECK(m_frame->document());
 
-  if (!m_frame->isNavigationAllowed())
+  if (isBackForwardLoadType(frameLoadType) && !m_frame->isNavigationAllowed())
     return;
 
   if (m_inStopAllLoaders)
@@ -1124,6 +1124,12 @@ void FrameLoader::load(const FrameLoadRequest& passedRequest,
                            ? nullptr
                            : m_frame->findFrameForNavigation(
                                  AtomicString(request.frameName()), *m_frame);
+
+  if (targetFrame && targetFrame->isLocalFrame() &&
+      !toLocalFrame(targetFrame)->isNavigationAllowed()) {

[dcheng, 2017/01/04 23:12:02]

We use targetFrame->navigate(), which (for local frames) delegates to
NavigationScheduler. NavigationScheduler::shouldScheduleNavigation() consults
isNavigationAllowed(), so how come we need to check this here as well?

[lfg, 2017/01/09 19:04:12]

targetFrame->navigate() just calls FrameLoader::load() when the argument is a
FrameLoadRequest. There are multiple definitions of LocalFrame::navigate().

[dcheng, 2017/01/09 19:17:30]

OK, this check should be in the block at 1133 - 1144 though, I think: we won't
target targetFrame at all otherwise.

[lfg, 2017/01/09 21:18:22]

Yes, that should be correct. Done.

+    return;
+  }
+
   NavigationPolicy policy = navigationPolicyForRequest(request);
   if (targetFrame && targetFrame != m_frame &&
       shouldNavigateTargetFrame(policy)) {
@@ -1150,6 +1156,8 @@ void FrameLoader::load(const FrameLoadRequest& passedRequest,
     return;
   }
 
+  CHECK(m_frame->isNavigationAllowed());

[dcheng, 2017/01/04 23:12:02]

I would be more comfortable with this being an early-return, since this is going
to be merged.

[lfg, 2017/01/09 19:04:12]

I've agree with that, but I still think that going forward we should document
this well and be more strict about wrong calls.

+
   const KURL& url = request.resourceRequest().url();
   FrameLoadType newLoadType = (frameLoadType == FrameLoadTypeStandard)
                                   ? determineFrameLoadType(request)
@@ -1558,7 +1566,7 @@ bool FrameLoader::shouldClose(bool isReload) {
 
   bool shouldClose = false;
   {
-    NavigationDisablerForUnload navigationDisabler;
+    NavigationDisablerForBeforeUnload navigationDisabler;
     size_t i;
 
     bool didAllowNavigation = false;