Mac: Require child AllocateGpuMemoryBuffer to not fail

content/child/child_gpu_memory_buffer_manager.cc

Index: content/child/child_gpu_memory_buffer_manager.cc
diff --git a/content/child/child_gpu_memory_buffer_manager.cc b/content/child/child_gpu_memory_buffer_manager.cc
index c83ceea64155878cb1e3e3ae0de17bff2c53f002..21a512f319453169e1e7632c6b96168355829a53 100644
--- a/content/child/child_gpu_memory_buffer_manager.cc
+++ b/content/child/child_gpu_memory_buffer_manager.cc
@@ -45,18 +45,13 @@ ChildGpuMemoryBufferManager::AllocateGpuMemoryBuffer(const gfx::Size& size,
       content::GetNextGenericSharedMemoryId(), size.width(), size.height(),
       format, usage, &handle);
   bool success = sender_->Send(message);
-  if (!success || handle.is_null())
-    return nullptr;
+  CHECK(success);
+  CHECK(!handle.is_null());
 
   scoped_ptr<GpuMemoryBufferImpl> buffer(GpuMemoryBufferImpl::CreateFromHandle(
       handle, size, format, usage,
       base::Bind(&DeletedGpuMemoryBuffer, sender_, handle.id)));
-  if (!buffer) {
-    sender_->Send(new ChildProcessHostMsg_DeletedGpuMemoryBuffer(
-        handle.id, gpu::SyncToken()));
-    return nullptr;
-  }
-
+  CHECK(buffer);

[reveman, 2015/12/04 01:47:04]

nit: I don't think this should be able to fail unless there's a bug in our code
and we shouldn't be using CHECKs for that in the general case. If you think this
check is useful for temporarily diagnosing GMB allocation failure then add a
TODO here about removing it later.

fyi, the CHECK(!handle.is_null()) above is different as that can fail as a
result of running out of os resources (e.g. system memory) which is not
something we can fully control and it's best to catch that as early as possible.

[ccameron, 2015/12/04 02:36:20]

I could picture it failing if, for instance, IOSurfaceLookupFromMachPort (from
ChildIOSurfaceManager::AcquireIOSurface, from
GpuMemoryBufferImplIOSurface::CreateFromHandle) requires allocating some sorts
of resources. I think that failure at creation time is more likely, but I'm
still curious if this will be hit.

   return buffer.Pass();
 }