Consolidate isolated origin subframes into existing processes.

content/browser/frame_host/render_frame_host_manager.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_frame_host_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <string>
@@ skipping 1244 matching lines @@
   // current one. If we didn't, we would have two RenderFrameHosts in the same
   // SiteInstance and the same frame, breaking lookup of RenderFrameHosts by
   // SiteInstance.
   if (force_swap)
     CHECK_NE(new_instance, current_instance);
 
   // Double-check that the new SiteInstance is associated with the right
   // BrowserContext.
   DCHECK_EQ(new_instance->GetBrowserContext(), browser_context);
 
+  // If |new_instance| is a new SiteInstance for a subframe with an isolated
+  // origin, set its process reuse policy so that such subframes are
+  // consolidated into existing processes for that isolated origin.
+  SiteInstanceImpl* new_instance_impl =
+      static_cast<SiteInstanceImpl*>(new_instance.get());
+  auto* policy = ChildProcessSecurityPolicyImpl::GetInstance();
+  if (!frame_tree_node_->IsMainFrame() && !new_instance_impl->HasProcess() &&
+      new_instance_impl->HasSite() &&
+      policy->IsIsolatedOrigin(url::Origin(new_instance_impl->GetSiteURL()))) {

[alexmos, 2017/06/01 20:47:58]

We could consider doing this for all subframes that require a dedicated process,
not just isolated origins.  Do you think that's worth doing here or in a
followup?

[Charlie Reis, 2017/06/01 22:27:47]

I like that idea.  It would probably be safe to do here, but doing it in a
followup is probably worthwhile-- that makes it less likely that the isolated
origin case is reverted if the general case turns out to have issues.

+    new_instance_impl->set_process_reuse_policy(
+        SiteInstanceImpl::ProcessReusePolicy::REUSE_PENDING_OR_COMMITTED_SITE);
+  }
+
   return new_instance;
 }
 
 RenderFrameHostManager::SiteInstanceDescriptor
 RenderFrameHostManager::DetermineSiteInstanceForURL(
     const GURL& dest_url,
     SiteInstance* source_instance,
     SiteInstance* current_instance,
     SiteInstance* dest_instance,
     ui::PageTransition transition,
@@ skipping 1581 matching lines @@
           delegate_->IsHidden()) {
     if (delegate_->IsHidden()) {
       render_frame_host_->GetView()->Hide();
     } else {
       render_frame_host_->GetView()->Show();
     }
   }
 }
 
 }  // namespace content