Bug 158404 – Web Inspector: resources don't show in resources/debugger sidebar after navigating inspected page back

• Status: NEW
• Component: Web Inspector

[Blaze Burg]

STEPS TO REPRODUCE:

1. Go to attached page
2. Open inspector to Resources or Debugger tab.
3. Navigate the inspected page away to another page
4. Press the back button or evaluate window.history.back()

EXPECTED:

Main resource appears in sidebar, along with any resources that were downloaded or failed when the page was loaded

ACTUAL:

Nothing appears in the sidebar at all

NOTES:

This appears to be related to the back-forward cache. If this is a cache hit, then WebCore will not tell the frontend about any new resource loads because it doesn't perform any loads at all to redisplay the page. If it's a miss, then it works fine because we have to re-download or revalidate resources.

I'm not sure how we should fix this.

 - We shouldn't disable the back-forward cache while inspecting for performance reasons. That also be bad because it would make it impossible to debug problems that web content may have related to the back-forward cache (like page visibility and throttling).

 - One option is to tell the inspector about the navigation type (specifically, whether it hit the back-forward cache), and have the frontend keep around past resource trees until they are purged from the back-forward cache. I don't think the backend can re-send this data, since the original request data is probably not kept around after loading a resource finishes.

[Radar WebKit Bug Importer]

<rdar://problem/26643004>

[Blaze Burg]

Created attachment 280563 [details]
Test case