This test was added in bug 1742985, but doesn't actually run on any platform with the GPU process enabled. (Due to bug 1495580 on windows, and because the GPU process isn't yet enabled on Android).

I added a function nsIGfxInfo.ensureGPUProcessReadyForTests which was supposed to wait until the GPU process has been restarted, allowing the test to function correctly. I also modified the check in GPUProcessHost::IsConnected for that to work. However, it still doesn't actually work as we need it to. If ensureGPUProcessReadyForTests is called immediately after we have killed the GPU process then it hasn't had time to notice that the process has been killed, and returns immediately.

This bug will fix the test by instead waiting for the compositor-reinitialized observer to be called. We can therefore also remove/revert the buggy ensureGPUProcessReadyForTests function.

Bug 1742985 added the test helper_zoom_after_gpu_process_restart.html,
but it doesn't actually get run on any platform with the GPU process
enabled. (Due to bug 1495580 on windows, and because the GPU process
isn't yet enabled on android.)

The test kills the GPU process, then tries to wait for it to be
restarted before proceeding. However, the function
ensureGPUProcessReadyForTests doesn't always work as intended, as the
GPUProcessManager may not have yet noticed that the process has been
killed, and therefore may return immediately from EnsureGPUReady.

This patch removes the buggy ensureGPUProcessReadyForTests function,
and instead makes the test wait for the "compositor-reinitialized"
topic to be observed.

https://hg.mozilla.org/mozilla-central/rev/cb58117c82a9

Moving GPU process bugs to the new GeckoView::Sandboxing component.