predictors: Add a origin for prefetch requests, remove the URL/host settings.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 4aaa9f02bf9a59715cae07f22e1c44c0ed97c2e8..86fcb3f8c4a693c5b79fc05fe5bac19785077a2f 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -893,6 +893,10 @@ const char kSpeculativeResourcePrefetchingDisabled[] = "disabled";
 // Speculative resource prefetching is enabled.
 const char kSpeculativeResourcePrefetchingEnabled[] = "enabled";
 
+// Speculative resource prefetching is enabled for external requests.
+const char kSpeculativeResourcePrefetchingEnabledExternal[] =
+    "enabled-external";

[pasko, 2016/11/29 14:44:44]

why not "enabled-external-only"? do you think it will confuse readers enough to
make them think this does not enable learning?

[Benoit L, 2016/11/29 17:02:51]

Done.

+
 // Speculative resource prefetching will only learn about resources that need to
 // be prefetched but will not prefetch them.
 const char kSpeculativeResourcePrefetchingLearning[] = "learning";