Shortcut ctrl+shift+T added on android.

components/sessions/content/content_platform_specific_tab_data.h

Index: components/sessions/content/content_platform_specific_tab_data.h
diff --git a/components/sessions/content/content_platform_specific_tab_data.h b/components/sessions/content/content_platform_specific_tab_data.h
index 1ccc6dd7c64448a5293bf466763f38a0cf73ecb7..1ad05051e5f3c77abfef372b90444ee07cd98a73 100644
--- a/components/sessions/content/content_platform_specific_tab_data.h
+++ b/components/sessions/content/content_platform_specific_tab_data.h
@@ -31,11 +31,22 @@ class SESSIONS_EXPORT ContentPlatformSpecificTabData
     return session_storage_namespace_.get();
   }
 
+  SessionID::id_type window_id() const {
+    return window_id_;

[sky, 2016/06/24 15:54:22]

Can you elaborate on why you need to add this here? In general I would prefer to
keep this class at just the parts needed by session restore. AFAICT the
window_id_ isn't generally needed by components/session. I you need to
associated arbitrary data with WebContents, use SupportsUserData.

[xingliu, 2016/06/24 16:48:44]

Thank you for the feedback,

The window_id here is used by android chrome to write the window id into
TabRestoreService::Tab. So during restoring, it can find the correct window.
TabRestoreService::Tab.browser_id is not used by android since LiveTabContext is
bypassed. The place where Tab.browser_id is bypassed on android is
TabRestoreServiceHelper::PopulateTab line 383.
 
The reason to read window id from TabRestoreService::Tab is that we're trying to
restore a tab when no parent tab context is given, so it can't find the window
id or browser id from WebContents in any existing tab.

[xingliu, 2016/06/24 17:52:29]

Or I can add function to access TabRestoreService::Tab entry from external class
to write the window id into TabRestoreService::Tab.browser_id, if this makes
more sense.

+  }
+
+  void SetWindowId(SessionID::id_type id) {

[sky, 2016/06/24 15:54:22]

set_window_id

[xingliu, 2016/06/24 16:48:44]

Will be fixed shortly.

+    window_id_ = id;
+  }
+
  private:
   // PlatformSpecificTabData:
   std::unique_ptr<PlatformSpecificTabData> Clone() override;
 
   scoped_refptr<content::SessionStorageNamespace> session_storage_namespace_;
+
+  // used to match android tab model id.
+  SessionID::id_type window_id_;

[sky, 2016/06/24 15:54:22]

This needs to be initialized in the member initialize list.

[xingliu, 2016/06/24 16:48:44]

Will be fixed shortly.

 };
 
 }  // namespace sessions