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..58559db0a5d44c30cd058b86dea5390dc4403913 100644
--- a/chrome/browser/extensions/api/declarative_content/content_action.cc
+++ b/chrome/browser/extensions/api/declarative_content/content_action.cc
@@ -7,6 +7,7 @@
 #include <map>
 
 #include "base/lazy_instance.h"
+#include "base/memory/linked_ptr.h"

[Devlin, 2015/01/20 17:51:04]

nit: Don't need this, right?

[Xi Han, 2015/01/21 21:30:16]

Sorry, forget to clean up.

 #include "base/strings/stringprintf.h"
 #include "base/values.h"
 #include "chrome/browser/extensions/api/declarative_content/content_constants.h"
@@ -22,6 +23,7 @@
 #include "content/public/browser/web_contents.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
+#include "extensions/common/consumer.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/extension_messages.h"
 #include "ui/gfx/image/image.h"
@@ -239,6 +241,33 @@ 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();
+  RequestContentScriptKeyToIDMap::iterator it = map.find(key);

[Devlin, 2015/01/20 17:51:05]

instead of lines 263 - 268, do:
if (it == map.end()) {
  it = map.insert(std::make_pair(key, ConsumerID(host_type, host_id,
instance_type, GetNextId()).first;
}
return it->second;

In addition to saving a line or two of code, it saves you from doing a duplicate
lookup on line 268.

[Xi Han, 2015/01/21 21:30:16]

Goods better, updated.

+  if (it != map.end())
+    return it->second;
+
+  map[key] = ConsumerID(host_type, key.host_id, instance_type,
+                        ConsumerID::GetNextID());
+  return map[key];
+}
+
 }  // namespace
 
 //
@@ -350,11 +379,13 @@ RequestContentScript::RequestContentScript(
     content::BrowserContext* browser_context,
     const Extension* extension,
     const ScriptData& script_data) {
-  InitScript(extension, script_data);
-
+  const RequestKey key(extension->id());
+  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 +393,8 @@ RequestContentScript::RequestContentScript(
     DeclarativeUserScriptMaster* master,
     const Extension* extension,
     const ScriptData& script_data) {
-  InitScript(extension, script_data);
-
   master_ = master;
+  InitScript(extension, script_data);
   AddScript();
 }
 
@@ -376,7 +406,7 @@ 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);