Move session_id.{cc,h} from chrome/browser/sessions to components/sessions

chrome/browser/sessions/session_tab_helper.cc

Index: chrome/browser/sessions/session_tab_helper.cc
diff --git a/chrome/browser/sessions/session_tab_helper.cc b/chrome/browser/sessions/session_tab_helper.cc
index 8435649f2385d162062312dc6cc9be7b67e9f671..c4c0e4e9983dff53d77b5d211f5b65d691f6de12 100644
--- a/chrome/browser/sessions/session_tab_helper.cc
+++ b/chrome/browser/sessions/session_tab_helper.cc
@@ -32,6 +32,21 @@ void SessionTabHelper::SetWindowID(const SessionID& id) {
           web_contents()->GetRenderViewHost()->GetRoutingID(), id.id()));
 }
 
+// static
+SessionID::id_type SessionTabHelper::IdForTab(const content::WebContents* tab) {
+  const SessionTabHelper* session_tab_helper =
+      tab ? SessionTabHelper::FromWebContents(tab) : NULL;
+  return session_tab_helper ? session_tab_helper->session_id().id() : -1;
+}
+
+// static
+SessionID::id_type SessionTabHelper::IdForWindowContainingTab(
+    const content::WebContents* tab) {
+  const SessionTabHelper* session_tab_helper =
+      tab ? SessionTabHelper::FromWebContents(tab) : NULL;
+  return session_tab_helper ? session_tab_helper->window_id().id() : -1;
+}
+
 void SessionTabHelper::RenderViewCreated(
     content::RenderViewHost* render_view_host) {
   render_view_host->Send(