Refactoring: de-couple Extensions from "script injection System" [render side] : 1

extensions/browser/guest_view/web_view/web_view_guest.cc

Index: extensions/browser/guest_view/web_view/web_view_guest.cc
diff --git a/extensions/browser/guest_view/web_view/web_view_guest.cc b/extensions/browser/guest_view/web_view/web_view_guest.cc
index 36418980eadde3a8fa1d9fd78e76eafe7215b33b..73fe4257c7627b301f5bb7f39c0f79482ed6e0d3 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest.cc
+++ b/extensions/browser/guest_view/web_view/web_view_guest.cc
@@ -59,6 +59,8 @@ namespace extensions {
 
 namespace {
 
+int current_script_injection_instance_id = 0;
+
 std::string WindowOpenDispositionToString(
   WindowOpenDisposition window_open_disposition) {
   switch (window_open_disposition) {
@@ -100,6 +102,10 @@ static std::string TerminationStatusToString(base::TerminationStatus status) {
   return "unknown";
 }
 
+int GetNextScriptInjectionInstanceID() {
+  return ++current_script_injection_instance_id;
+}
+
 std::string GetStoragePartitionIdFromSiteURL(const GURL& site_url) {
   const std::string& partition_id = site_url.query();
   bool persist_storage = site_url.path().find("persist") != std::string::npos;
@@ -185,6 +191,8 @@ using WebViewKey = std::pair<int, int>;
 using WebViewKeyToIDMap = std::map<WebViewKey, int>;
 static base::LazyInstance<WebViewKeyToIDMap> web_view_key_to_id_map =
     LAZY_INSTANCE_INITIALIZER;
+static base::LazyInstance<WebViewKeyToIDMap> script_injection_instance_id_map =

[Devlin, 2015/02/06 00:28:41]

It bothers me that we have multiple different maps of "webview to unique id". 
We should only ever need one unique id per webview, right?

[Xi Han, 2015/02/06 17:21:45]

We would like to have just one function, but the implementation of the Rule
Registry part calls RulesRegistryService::GetNextRulesRegistryID() to generate
the rule registry id, since the assignment of id is done by
RulesRegistryService. To generate the script_injection_instance_id, however, we
don't need the RulesRegistryService to make a decision, so we have to use
another map to stored the kv pairs, since the value may be different for the
same key in two maps. 

[Devlin, 2015/02/06 18:48:36]

But the RulesRegistry one is going away, right?

[Xi Han, 2015/02/06 19:45:33]

Hmmm, I don't think so, because the declarative webrequest still needs this map
to get an rule registry id for <webview>. 

[Devlin, 2015/02/09 17:40:24]

Ah, right.  In that case, can we make GetRulesRegistryId more generic, and just
say GetUniqueWebviewId, and use that for both rules registry and script
injection?  It just seems silly to have two maps used for generating a unique id
for a webview.

[Xi Han, 2015/02/09 23:28:11]

As discussed offline, we will still keeps two maps but will reorganize the code
and make it more generic.

+     LAZY_INSTANCE_INITIALIZER;
 
 // static
 int WebViewGuest::GetOrGenerateRulesRegistryID(
@@ -208,6 +216,25 @@ int WebViewGuest::GetOrGenerateRulesRegistryID(
 }
 
 // static
+int WebViewGuest:: GetOrGenerateScriptInjectionInstanceID(
+    int embedder_process_id,
+    int guest_instance_id ) {
+  if (!(embedder_process_id && guest_instance_id))
+    return Host::kDefaultInstanceId;
+
+  WebViewKey key = std::make_pair(embedder_process_id, guest_instance_id);
+  WebViewKeyToIDMap& script_injection_ids =
+      script_injection_instance_id_map.Get();
+  auto it = script_injection_ids.find(key);
+  if (it != script_injection_ids.end())
+    return it->second;
+
+  int script_injection_instance_id = GetNextScriptInjectionInstanceID();
+  script_injection_ids[key] = script_injection_instance_id;
+  return script_injection_instance_id;
+}
+
+// static
 int WebViewGuest::GetViewInstanceId(WebContents* contents) {
   auto guest = FromWebContents(contents);
   if (!guest)
@@ -294,6 +321,10 @@ void WebViewGuest::DidInitialize(const base::DictionaryValue& create_params) {
       owner_web_contents()->GetRenderProcessHost()->GetID(),
       view_instance_id());
 
+  GetOrGenerateScriptInjectionInstanceID(
+      owner_web_contents()->GetRenderProcessHost()->GetID(),
+      guest_instance_id());
+
   // We must install the mapping from guests to WebViews prior to resuming
   // suspended resource loads so that the WebRequest API will catch resource
   // requests.
@@ -321,6 +352,7 @@ void WebViewGuest::EmbedderWillBeDestroyed() {
   WebViewKey key(owner_web_contents()->GetRenderProcessHost()->GetID(),
                  view_instance_id());
   web_view_key_to_id_map.Get().erase(key);
+  script_injection_instance_id_map.Get().erase(key);
 
   content::BrowserThread::PostTask(
       content::BrowserThread::IO,