Create a mechanism define declarative rules via the extension manifest.

extensions/browser/api/declarative/rules_registry.cc

Index: extensions/browser/api/declarative/rules_registry.cc
diff --git a/extensions/browser/api/declarative/rules_registry.cc b/extensions/browser/api/declarative/rules_registry.cc
index dfd9c35260ace0ea706aa383d78d355c8177e57b..bcc069b9fcb87d7ad4ce311877805d68c1a959b3 100644
--- a/extensions/browser/api/declarative/rules_registry.cc
+++ b/extensions/browser/api/declarative/rules_registry.cc
@@ -19,6 +19,7 @@
 #include "content/public/browser/notification_source.h"
 #include "extensions/browser/api/declarative/rules_cache_delegate.h"
 #include "extensions/browser/extension_prefs.h"
+#include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/browser/state_store.h"
 #include "extensions/common/extension.h"
@@ -226,9 +227,21 @@ void RulesRegistry::OnExtensionLoaded(const std::string& extension_id) {
   DCHECK_CURRENTLY_ON(owner_thread());
   std::vector<linked_ptr<Rule> > rules;
   GetAllRules(extension_id, &rules);
-  std::string error = AddRulesImpl(extension_id, rules);
-  if (!error.empty())
-    LOG(ERROR) << error;
+  if (rules.empty()) {
+    // If no rules have been registered yet, check if there are any rules

[not at google - send to devlin, 2015/06/02 22:44:50]

Why only if there are no rules registered yet? It seems a perfectly reasonable
use case to have a set of rules in the manifest, with a dynamic set to add
later.

[danduong, 2015/06/04 23:06:37]

Done.

+    // defined in the extension manifest to add.
+    const Extension* extension =
+        ExtensionRegistry::Get(browser_context())
+            ->GetExtensionById(extension_id, ExtensionRegistry::EVERYTHING);
+    const base::ListValue* value = NULL;
+    if (extension->manifest()->GetList(event_name_, &value)) {
+      AddRules(extension_id, RulesFromValue(value));
+    }
+  } else {
+    std::string error = AddRulesImpl(extension_id, rules);
+    if (!error.empty())
+      LOG(ERROR) << error;
+  }
 }
 
 size_t RulesRegistry::GetNumberOfUsedRuleIdentifiersForTesting() const {