Adds a way to determine id of content handler that created app

mojo/shell/content_handler_connection.cc

Index: mojo/shell/content_handler_connection.cc
diff --git a/mojo/shell/content_handler_connection.cc b/mojo/shell/content_handler_connection.cc
index dd3c5cb9e1a9e496a3e69cdd9a958ad4909d5017..0dba7f9db60b81d3c63d9553cbba643614ea1b9a 100644
--- a/mojo/shell/content_handler_connection.cc
+++ b/mojo/shell/content_handler_connection.cc
@@ -4,6 +4,7 @@
 
 #include "mojo/shell/content_handler_connection.h"
 
+#include "base/bind.h"
 #include "mojo/shell/application_manager.h"
 
 namespace mojo {
@@ -15,17 +16,24 @@ ContentHandlerConnection::ContentHandlerConnection(
     const GURL& content_handler_url,
     const GURL& requestor_url,
     const std::string& qualifier,
-    const CapabilityFilter& filter)
+    const CapabilityFilter& filter,
+    uint32_t id)
     : manager_(manager),
       content_handler_url_(content_handler_url),
       content_handler_qualifier_(qualifier),
-      connection_closed_(false) {
+      connection_closed_(false),
+      id_(id),
+      got_nested_content_handler_id_(false),
+      nested_content_handler_id_(0u),
+      weak_ptr_factory_(this) {
   ServiceProviderPtr services;
   mojo::URLRequestPtr request(mojo::URLRequest::New());
   request->url = mojo::String::From(content_handler_url.spec());
   manager->ConnectToApplication(
-      originator, request.Pass(), qualifier, requestor_url, GetProxy(&services),
-      nullptr, filter, base::Closure());
+      originator, request.Pass(), qualifier, requestor_url, id,
+      GetProxy(&services), nullptr, filter, base::Closure(),
+      base::Bind(&ContentHandlerConnection::OnGotNestedContentHandlerID,
+                 weak_ptr_factory_.GetWeakPtr()));
   MessagePipe pipe;
   content_handler_.Bind(
       InterfacePtrInfo<ContentHandler>(pipe.handle0.Pass(), 0u));
@@ -42,11 +50,36 @@ void ContentHandlerConnection::CloseConnection() {
   delete this;
 }
 
+void ContentHandlerConnection::ScheduleTargetIdCallback(
+    const Shell::ConnectToApplicationCallback& connect_callback) {
+  if (got_nested_content_handler_id_)
+    connect_callback.Run(content_handler_id_for_callback());
+  else
+    pending_content_handler_id_callbacks_.push_back(connect_callback);
+}
+
 ContentHandlerConnection::~ContentHandlerConnection() {
   // If this DCHECK fails then something has tried to delete this object without
   // calling CloseConnection.
   DCHECK(connection_closed_);
 }
 
+void ContentHandlerConnection::OnGotNestedContentHandlerID(
+    uint32_t content_handler_id) {
+  DCHECK(!got_nested_content_handler_id_);
+  got_nested_content_handler_id_ = true;
+  nested_content_handler_id_ = content_handler_id;
+  for (auto callback : pending_content_handler_id_callbacks_)
+    callback.Run(content_handler_id_for_callback());
+  pending_content_handler_id_callbacks_.clear();
+}
+
+uint32_t ContentHandlerConnection::content_handler_id_for_callback() const {
+  return nested_content_handler_id_ ==
+                 ApplicationManager::kInvalidContentHandlerID
+             ? id_
+             : nested_content_handler_id_;
+}
+
 }  // namespace shell
 }  // namespace mojo