Revert 283678 "Refactor code that defers extension background pa..."

Revert 283678 "Refactor code that defers extension background pa..."

This broke Chrome OS valgrind bots, for example:
http://build.chromium.org/p/chromium.memory.fyi/builders/Chromium%20OS%20%28valgrind%29%284%29/builds/27033

> Refactor code that defers extension background page loading
> 
> src/extensions depends on chrome::NOTIFICATION_PROFILE_CREATED to support deferred loading of extension background pages when the profile isn't ready yet. This is a layering violation.
> 
> * Remove Chrome concepts like "browser window ready" and "profile created" from ProcessManager. Introduce ProcessManagerDelegate with a general concept of deferring background page loading.
> * Consolidate all the tricky Chrome-specific background page loading rules into ChromeProcessManagerDelegate. This keeps all the rules in one place. Annotate each block of special case code with the bug that inspired it.
> * Extend unit test coverage for ProcessManager.
> 
> This will make it easier to eliminate chrome::NOTIFICATION_PROFILE_DESTROYED in ProcessManager in a later CL.
> 
> BUG=392658
> TEST=unit_tests ProcessManagerTest, browser_tests ProcessManagerBrowserTest, manual
> 
> Review URL: https://codereview.chromium.org/381283002

TBR=jamescook@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283801

[James Cook, 2014-07-17 17:21:48]

Committed patchset #1 manually as r283801.