Revert of Do not create proxy hosts in the subtree of navigating frame. (patchset #11 id:200001 of https://codereview.chromium.org/536143002/)

Reason for revert:
SitePerProcessBrowserTest.ProxyCreationSkipsSubtree repeatedly fails on Mac with ASAN reporting use-after-free, see:

http://build.chromium.org/p/chromium.memory/builders/Mac%20ASan%2064%20Tests%20%281%29/builds/2174
http://build.chromium.org/p/chromium.fyi/builders/Chromium%20Mac%2010.8%20Buildrunner/builds/19009

@Nasko, as there are some simultaneous breakages right now, so I could not investigate this further and opted to revert the whole thing to get the tree green ASAP.

Snippets from test log:

ASSERTION FAILED: !localFrame || (localFrame->isLocalFrame())
../../third_party/WebKit/Source/core/frame/LocalFrame.h(253) : blink::LocalFrame *blink::toLocalFrame(blink::Frame *)
../../content/browser/site_per_process_browsertest.cc:690: Failure
Value of: child->child_count()
  Actual: 2
Expected: 0U
Which is: 0

Original issue's description:
> Do not create proxy hosts in the subtree of navigating frame.
>
> When a frame is navigating cross-process, its existing document will be completely destroyed and all child frames will be gone. This means that we don't need to create proxy objects for the new SiteInstance in the subtree of the navigating frame.
>
> BUG=357747
>
> Committed: https://crrev.com/faab4288197b20b73610aad3e5579751b0c3a97b
> Cr-Commit-Position: refs/heads/master@{#294520}

TBR=ajwong@chromium.org,kenrb@chromium.org,jam@chromium.org,creis@chromium.org,dmazzoni@chromium.org,nasko@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=357747

Review URL: https://codereview.chromium.org/565103002

Cr-Commit-Position: refs/heads/master@{#294552}

1 files changed, 7 insertions, 15 deletions

diff --git a/content/browser/frame_host/frame_tree.cc b/content/browser/frame_host/frame_tree.cc
index d5a183f..3415e46 100644
--- a/content/browser/frame_host/frame_tree.cc
+++ b/content/browser/frame_host/frame_tree.cc
@@ -52,8 +52,13 @@ bool ResetNodesForNewProcess(RenderViewHost* render_view_host,
   return true;
 }
 
-bool CreateProxyForSiteInstance(const scoped_refptr<SiteInstance>& instance,
+bool CreateProxyForSiteInstance(FrameTreeNode* source_node,
+                                const scoped_refptr<SiteInstance>& instance,
                                 FrameTreeNode* node) {
+  // Skip the node that initiated the creation.
+  if (source_node == node)
+    return true;
+
   node->render_manager()->CreateRenderFrameProxy(instance.get());
   return true;
 }
@@ -123,21 +128,12 @@ FrameTreeNode* FrameTree::FindByRoutingID(int routing_id, int process_id) {
 
 void FrameTree::ForEach(
     const base::Callback<bool(FrameTreeNode*)>& on_node) const {
-  ForEach(on_node, NULL);
-}
-
-void FrameTree::ForEach(
-    const base::Callback<bool(FrameTreeNode*)>& on_node,
-    FrameTreeNode* skip_this_subtree) const {
   std::queue<FrameTreeNode*> queue;
   queue.push(root_.get());
 
   while (!queue.empty()) {
     FrameTreeNode* node = queue.front();
     queue.pop();
-    if (skip_this_subtree == node)
-      continue;
-
     if (!on_node.Run(node))
       break;
 
@@ -197,11 +193,7 @@ void FrameTree::CreateProxiesForSiteInstance(
   }
 
   scoped_refptr<SiteInstance> instance(site_instance);
-
-  // Proxies are created in the FrameTree in response to a node navigating to a
-  // new SiteInstance. Since |source|'s navigation will replace the currently
-  // loaded document, the entire subtree under |source| will be removed.
-  ForEach(base::Bind(&CreateProxyForSiteInstance, instance), source);
+  ForEach(base::Bind(&CreateProxyForSiteInstance, source, instance));
 }
 
 void FrameTree::ResetForMainFrameSwap() {