Bug 857653 - Fix leak in AudioChannelAgent by making it hold a weak ref to nsHTMLMediaElement.
Bug 844323 - WIP: Move procesprioritymanager to main process.

Don't forget to remove ProcessPriorityManager-old.cpp
Bug 844323 - ProcessPriorityManager tests.
Adding test_Visibility.html.
Bug XXX - Remove some warnings in toolkit/xre/nsAppRunner.cpp.
Bug XXX - Remove a warning in the startupcache.
Use a pref to in nsHTMLMediaElement to control whether we talk to the audio service.

Previously, we used #ifdef B2G.  Using a pref allows us to write mochitests which run in desktop Firefox that test the audio service and its interaction with other components.
Adding audio process priority test.
Adding test_MultipleFrames.
Remove XXX comment in ProcessPriorityManager.
Switch xpcom/base/StaticPtr from NULL to nullptr, and add a necessary include.
Change ProcessPriorityManager's export directory.

It was mozilla/dom/ipc/ before, but this changes it to mozilla/, which matches the file's namespace.
Move process preallocation logic out of ContentParent and into a new file, PreallocatedProcessManager.

Also make the PreallocatedProcessManager respond to pref changes.  This allows us to write a test involving the preallocated process.
Add test_Preallocated.
WIP dom/content changes.
TEMP fixing race in AsyncChannel.