"Top Document Isolation" mode

content/common/site_isolation_policy.cc

Index: content/common/site_isolation_policy.cc
diff --git a/content/common/site_isolation_policy.cc b/content/common/site_isolation_policy.cc
index 694c9db3336be49465f81223f9f2f49e70575a07..a0b33ab6aa4666c5274e117d94a764322181dfb4 100644
--- a/content/common/site_isolation_policy.cc
+++ b/content/common/site_isolation_policy.cc
@@ -15,8 +15,8 @@ namespace content {
 
 // static
 bool SiteIsolationPolicy::AreCrossProcessFramesPossible() {
-  return base::CommandLine::ForCurrentProcess()->HasSwitch(
-             switches::kSitePerProcess) ||
+  return UseDedicatedProcessesForAllSites() ||
+         IsTopDocumentIsolationEnabled() ||
          GetContentClient()->IsSupplementarySiteIsolationModeEnabled() ||
          BrowserPluginGuestMode::UseCrossProcessFramesForGuests();
 }
@@ -28,6 +28,16 @@ bool SiteIsolationPolicy::UseDedicatedProcessesForAllSites() {
 }
 
 // static
+bool SiteIsolationPolicy::IsTopDocumentIsolationEnabled() {
+  // --site-per-process trumps --isolate-top-document.

[Charlie Reis, 2016/03/25 19:47:13]

nit: --top-document-isolation

This reminds me-- is there an easy way to run try jobs with custom command line
flags?  It'd be good to run the tests with only --isolate-extensions (to make
sure we don't regress) and with both --isolate-extensions and
--top-document-isolation (to make sure things work when a TDI user is in our
Finch trial).

[ncarter (slow), 2016/03/28 22:00:29]

I'm not sure about the tryjobs, but I was planning on looking at that soon by
writing some chrome browser tests that set both flags. This is on my tracking
list.

[Charlie Reis, 2016/03/29 17:17:12]

Sounds good.  We'll also be running your test class with --site-per-process (on
the Linux FYI bot) and --isolate-extensions (on the Win FYI bot), so we will
have some coverage.

+  if (UseDedicatedProcessesForAllSites())
+    return false;
+
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kTopDocumentIsolation);
+}
+
+// static
 bool SiteIsolationPolicy::UseSubframeNavigationEntries() {
   // Enable the new navigation history behavior if any manner of site isolation
   // is active.