Introduce support for origins that require process isolation.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 224c03243d067c2ea952583fff28cb72c3617eb3..1aaeaa6d964b33f80ac7ef0a9359c385045b56ab 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -603,6 +603,11 @@ const char kInProcessGPU[]                  = "in-process-gpu";
 // connection from the browser before killing itself.
 const char kIPCConnectionTimeout[]          = "ipc-connection-timeout";
 
+// Require dedicated processes for a set of origins, specified as a
+// comma-separated list. For example:
+//   --isolate-origins=https://www.foo.com,https://www.bar.com
+const char kIsolateOrigins[] = "isolate-origins";
+
 // Chrome is running in Mash.
 const char kIsRunningInMash[] = "is-running-in-mash";