import changes from rmottola/Arctic-Fox:

- Revert Bug 1125848 - Consolidate PCompositor's creation-destruction logic because of 10.7 MacOS bustage (ceda5a133)
- adapt assertion to be as introduced in Bug 1125848 (877071282)
- Bug 1160190 followup. Make ServiceWorker actually disabled on mulet so we can reopen the CLOSED TREE. r=bkelly (1a03ee7c2)
- Bug 1123846 - Restrict some activities to be provided by the system app r=ferjm (c7ca76805)
- fix header include order (01b1289df)
- Bug 1151644 - Don't disallow the basic compositor backend. r=jrmuizel (b70633afd)
- Bug 1155823 - Properly shutdown the CompositorVsyncDispatcher. r=kats (a3dee13e8)
- add gfxCrashReporterUtils as of 1180688  2015-07-13 (433fa6bdb)
- Bug 1029673 - Correctly report OMTC compositing in crash reports - r=Bas (87fc22936)
- Bug 1180688 - Detect whether the widget will be able to present frames with BasicCompositor on Mac. r=mstange (842ed309f)

gfx/layers/basic/BasicCompositor.cpp

@@ -82,6 +82,12 @@ BasicCompositor::~BasicCompositor()
   MOZ_COUNT_DTOR(BasicCompositor);
 }
 
+bool
+BasicCompositor::Initialize()
+{
+  return mWidget ? mWidget->InitCompositor(this) : false;
+};
+
 int32_t
 BasicCompositor::GetMaxTextureSize() const
 {