Introduce HostID and de-couple Extensions from "script injection System" [browser side]

chrome/browser/extensions/api/declarative_content/content_action.cc

Index: chrome/browser/extensions/api/declarative_content/content_action.cc
diff --git a/chrome/browser/extensions/api/declarative_content/content_action.cc b/chrome/browser/extensions/api/declarative_content/content_action.cc
index e0ff006e16d05bc8418a6014f331bb6300debe48..25641812a9a19fdbb27e77b5a37863bf1172b4cb 100644
--- a/chrome/browser/extensions/api/declarative_content/content_action.cc
+++ b/chrome/browser/extensions/api/declarative_content/content_action.cc
@@ -22,6 +22,7 @@
 #include "content/public/browser/web_contents.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
+#include "extensions/common/consumer_id.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/extension_messages.h"
 #include "ui/gfx/image/image.h"
@@ -239,6 +240,33 @@ struct ContentActionFactory {
 base::LazyInstance<ContentActionFactory>::Leaky
     g_content_action_factory = LAZY_INSTANCE_INITIALIZER;
 
+using RequestContentScriptKey = RequestContentScript::RequestKey;
+
+using RequestContentScriptKeyToIDMap =
+    std::map<RequestContentScriptKey, ConsumerID>;
+
+// A map of ConsumerIDs for the given RequestContentScript ids.
+// Different types of input ids need to define their own maps to store the
+// mappings from ids to ConsumerIDs.
+base::LazyInstance<RequestContentScriptKeyToIDMap>
+    request_content_script_key_to_id_map_ = LAZY_INSTANCE_INITIALIZER;
+
+// Looks up and returns the ConsumerID by the given RequestContentScriptKey;
+// if one does not exist, a new object will be created and returned.
+const ConsumerID& GetConsumerID(const RequestContentScriptKey& key,
+                                ConsumerID::HostType host_type,
+                                ConsumerID::InstanceType instance_type) {
+  RequestContentScriptKeyToIDMap& map =
+      request_content_script_key_to_id_map_.Get();
+  auto it = map.find(key);
+  if (it == map.end()) {
+    it = map.insert(std::make_pair(key,
+                                   ConsumerID(host_type, key, instance_type,
+                                              true /* is_declarative*/))).first;
+  }
+  return it->second;
+}
+
 }  // namespace
 
 //
@@ -350,11 +378,13 @@ RequestContentScript::RequestContentScript(
     content::BrowserContext* browser_context,
     const Extension* extension,
     const ScriptData& script_data) {
-  InitScript(extension, script_data);
-
+  const RequestKey key(extension->id());

[Devlin, 2015/01/21 23:25:20]

I think the typedef to RequestKey actually makes it harder for me to tell what's
going on here, not to mention requiring you to make a copy of extension->id(). 
Can we just take out the typedef completely?

[Xi Han, 2015/01/22 17:19:36]

Sorry, but no. To support <webview>, we need to extend the struct RequestKey,
and is why I define it as a struct in the first place. I put a TODO on top of
where the thatRequestKey is defined (refer to content_action.h line 99),
hopefully this commend can explain my purpose to introduce this struct.

+  const ConsumerID& consumer_id =
+      GetConsumerID(key, ConsumerID::EXTENSIONS, ConsumerID::TAB);
   master_ = ExtensionSystem::Get(browser_context)
                 ->declarative_user_script_manager()
-                ->GetDeclarativeUserScriptMasterByID(extension->id());
+                ->GetDeclarativeUserScriptMasterByID(consumer_id);
+  InitScript(extension, script_data);
   AddScript();
 }
 
@@ -362,9 +392,8 @@ RequestContentScript::RequestContentScript(
     DeclarativeUserScriptMaster* master,
     const Extension* extension,
     const ScriptData& script_data) {
-  InitScript(extension, script_data);
-
   master_ = master;
+  InitScript(extension, script_data);
   AddScript();
 }
 
@@ -376,7 +405,7 @@ RequestContentScript::~RequestContentScript() {
 void RequestContentScript::InitScript(const Extension* extension,
                                       const ScriptData& script_data) {
   script_.set_id(UserScript::GenerateUserScriptID());
-  script_.set_extension_id(extension->id());
+  script_.set_consumer_id(master_->consumer_id());
   script_.set_run_location(UserScript::BROWSER_DRIVEN);
   script_.set_match_all_frames(script_data.all_frames);
   script_.set_match_about_blank(script_data.match_about_blank);