Introduce support for origins that require process isolation.

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 b3db97ede58b4a304fa8f37b0a76786b1d864658..6b6db62e8f171eef58119ed52239ff608277c3f6 100644
--- a/content/common/site_isolation_policy.cc
+++ b/content/common/site_isolation_policy.cc
@@ -19,7 +19,7 @@ bool SiteIsolationPolicy::AreCrossProcessFramesPossible() {
 // investigated.
 #if defined(OS_ANDROID)
   return UseDedicatedProcessesForAllSites() ||
-         IsTopDocumentIsolationEnabled() ||
+         IsTopDocumentIsolationEnabled() || AreIsolatedOriginsEnabled() ||
          GetContentClient()->IsSupplementarySiteIsolationModeEnabled() ||
          base::FeatureList::IsEnabled(::features::kGuestViewCrossProcessFrames);
 #else
@@ -43,4 +43,14 @@ bool SiteIsolationPolicy::IsTopDocumentIsolationEnabled() {
       switches::kTopDocumentIsolation);
 }
 
+// static
+bool SiteIsolationPolicy::AreIsolatedOriginsEnabled() {
+  // TODO(alexmos): This currently assumes that isolated origins are only added
+  // via the command-line switch, which may not be true in the future.  Remove

[Charlie Reis, 2017/05/05 23:18:51]

Ooh, that's a problem for adding a public API (e.g., for sign-in).

Do you think we can get AreCrossProcessFramesPossible enabled on Android in
time?  Or maybe we don't need the API on Android?

[alexmos, 2017/05/16 17:26:38]

Per offline email thread, the sign-in isolation will be initially needed for
desktop only.  So we don't need to support Android for now.  That said, Ken said
he isn't aware of any other outstanding issues other than improving Android test
coverage and that perf regression, and we should keep pushing on those to enable
this soon.

+  // this function when AreCrossProcessFramesPossible becomes true on Android
+  // above.
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kIsolateOrigins);
+}
+
 }  // namespace content