Plumb document's strict mixed content checking for RemoteFrames

content/browser/frame_host/render_frame_host_manager.cc

Index: content/browser/frame_host/render_frame_host_manager.cc
diff --git a/content/browser/frame_host/render_frame_host_manager.cc b/content/browser/frame_host/render_frame_host_manager.cc
index 96d6c1f6d836ff6dc84fe017d5e220c0403fd812..7a19488f8d04619bcbf7240dae82c571da40633b 100644
--- a/content/browser/frame_host/render_frame_host_manager.cc
+++ b/content/browser/frame_host/render_frame_host_manager.cc
@@ -1184,6 +1184,15 @@ void RenderFrameHostManager::OnDidUpdateName(const std::string& name) {
   }
 }
 
+void RenderFrameHostManager::OnDidUpdateShouldEnforceStrictMixedContentChecking(
+    bool should_enforce) {
+  for (const auto& pair : *proxy_hosts_) {

[alexmos, 2015/12/11 02:52:27]

Are there other situations in which another frame's strict mixed content flag is
needed, other than inheriting it for new child frames?  
This logic is probably still fine, but I'm just curious how we might go about
optimizing the number of IPCs we send in the future.

Also, is the flag inherited for popups/openers (since proxy_hosts_ might include
those)?  

If inheriting across openers isn't needed, we shouldn't need this in default
Chrome, so it would be good to add a 
  if (!SiteIsolationPolicy::AreCrossProcessFramesPossible())
    return;

before the loop.  (We would only have popup/opener proxies if cross-process
frames are off).

[estark, 2015/12/12 01:35:43]

Well, it's checked whenever mixed content loads in a child frame. That is, if
https://foo.com has a child frame to https://bar.com which tries to load mixed
content, we need to check the https://foo.com flag:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

(On that line, |mixedFrame| will be the top-level frame in this case.)
Done. It's not needed for openers.

+    pair.second->Send(
+        new FrameMsg_DidUpdateShouldEnforceStrictMixedContentChecking(
+            pair.second->GetRoutingID(), should_enforce));
+  }
+}
+
 void RenderFrameHostManager::OnDidUpdateOrigin(const url::Origin& origin) {
   if (!SiteIsolationPolicy::IsSwappedOutStateForbidden())
     return;