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Viewing changes to chromium-extension/unity-webapps-binding.js
- Committer: Tarmac
- Date: 2013-07-08 15:04:14 UTC
- mfrom: (224.1.1 fix-chromium-28-support)
- Revision ID: tarmac-20130708150414-2krskytsa61xd6v7
[Impact]
Workaround for an issue with Chromium 27 and 28 and Webapps. Webapps stopped working altogether with those chromium versions. What happened is that any javascript callback function that was called (whatever the stage) from chromium's internal could not access the NPAPI plugin variable (_uwa) that is a javascript object that is a bridge to the WebApps NPAPI plugin. Accessing the variable throws with an exception "NPObject has been deleted" (which is not the case).
The workaround rebinds the variable for every callback to the plugin node.
TECHNICAL DETAILS:
-----------------
There has been some changes recently in chromium 27+ around the v8 bindings' templates separated by world type (either page world or content script private world). Although I am not sure, it seemed to have an impact somewhere in the lookup location for V8NPObject v8 binding variables.
The "NPOBJect has been deleted" exception first occurs when webapps callback in the context_prepare() callback (from a native NPAPI function) that tries to call the plugin using _uwa. The variable is just closed over in the callback but is being looked up in the v8 binding for NPAPI (npObjectInvokeImpl() in WebCore/bindings/v8/V8NPObject.cpp) in the wrong World (page world instead of content script world).
The V8NPObject binding for the NPAPI plugin is apparently created properly (tagged w/ the proper world id) but somewhere along the line (copying?) something goes wrong.
[Test Case]
1. install the unity-chromium-extension,
2. open chromium 28 and make sure that the extension is properly detected (chrome://extensions),
3. go to e.g. facebook.com or bbc.co.uk./news,
4. make sure that a launcher icon appears and the webapps integrates (notifications for bbc and messaging menu for facebook),
[Regression Potential]
None since the fix is strictly confined in the webapps extension and webapps are currently broken.
Approved by PS Jenkins bot, Víctor R. Ruiz.
Workaround for an issue with Chromium 27 and 28 and Webapps. Webapps stopped working altogether with those chromium versions. What happened is that any javascript callback function that was called (whatever the stage) from chromium's internal could not access the NPAPI plugin variable (_uwa) that is a javascript object that is a bridge to the WebApps NPAPI plugin. Accessing the variable throws with an exception "NPObject has been deleted" (which is not the case).
The workaround rebinds the variable for every callback to the plugin node.
TECHNICAL DETAILS:
-----------------
There has been some changes recently in chromium 27+ around the v8 bindings' templates separated by world type (either page world or content script private world). Although I am not sure, it seemed to have an impact somewhere in the lookup location for V8NPObject v8 binding variables.
The "NPOBJect has been deleted" exception first occurs when webapps callback in the context_prepare() callback (from a native NPAPI function) that tries to call the plugin using _uwa. The variable is just closed over in the callback but is being looked up in the v8 binding for NPAPI (npObjectInvokeImpl() in WebCore/bindings/v8/V8NPObject.cpp) in the wrong World (page world instead of content script world).
The V8NPObject binding for the NPAPI plugin is apparently created properly (tagged w/ the proper world id) but somewhere along the line (copying?) something goes wrong.
[Test Case]
1. install the unity-chromium-extension,
2. open chromium 28 and make sure that the extension is properly detected (chrome://extensions),
3. go to e.g. facebook.com or bbc.co.uk./news,
4. make sure that a launcher icon appears and the webapps integrates (notifications for bbc and messaging menu for facebook),
[Regression Potential]
None since the fix is strictly confined in the webapps extension and webapps are currently broken.
Approved by PS Jenkins bot, Víctor R. Ruiz.
added
removed
chromium-extension/unity-webapps-binding.js
