Introduce lock screen app context to extension features

extensions/browser/process_map.cc

Index: extensions/browser/process_map.cc
diff --git a/extensions/browser/process_map.cc b/extensions/browser/process_map.cc
index b3100201d011331d40fc8839a82b28b61fc92a24..c12c63578f8fd30289839290e9296fccda0d39ca 100644
--- a/extensions/browser/process_map.cc
+++ b/extensions/browser/process_map.cc
@@ -116,8 +116,8 @@ std::set<std::string> ProcessMap::GetExtensionsInProcess(int process_id) const {
 Feature::Context ProcessMap::GetMostLikelyContextType(
     const Extension* extension,
     int process_id) const {
-  // WARNING: This logic must match Dispatcher::ClassifyJavaScriptContext, as
-  // much as possible.
+  // WARNING: This logic must match ScriptContextSet::ClassifyJavaScriptContext,
+  // as much as possible.
 
   if (content::ChildProcessSecurityPolicy::GetInstance()->HasWebUIBindings(
           process_id)) {
@@ -140,7 +140,8 @@ Feature::Context ProcessMap::GetMostLikelyContextType(
     return Feature::BLESSED_WEB_PAGE_CONTEXT;
   }
 
-  return Feature::BLESSED_EXTENSION_CONTEXT;
+  return is_lock_screen_context_ ? Feature::LOCK_SCREEN_EXTENSION_CONTEXT

[Devlin, 2017/06/03 02:19:14]

If we expect no other lock-screen-type contexts, maybe it'd make sense to put
this at the top?

if (is_lock_screen_context_)
  return FEATURE::LOCK_SCREEN_CONTEXT;

if (content::ChildProcess....)

return Feature::BLESSED_EXTENSION_CONTEXT;

Because we *are* determining that any lock screen context is considered a lock
screen extension context, right?  Or are we anticipating having multiple
processes on the lock screen, some of which are "blessed" lock screen contexts,
and others that would be "web-page like" contexts?

[tbarzic, 2017/06/05 19:35:40]

At the moment, we could have web-page like contexts, in particular lock screen
UI is currently implemented as webui (though, that will probably change in near
future).

For content scripts/hosted apps, these should never be active for lock_screen
context, so it might be better to have a CHECK(!is_lock_screen_context_) or
return unspecified context instead of forcing LOCK_SCREEN_EXTENSION_CONTEXT.
WDYT?

+                                 : Feature::BLESSED_EXTENSION_CONTEXT;
 }
 
 }  // namespace extensions