LocalSurfaceIdProvider to use default LSI

Previously, ParentLocalSurfaceIdAllocator would default to an invalid
LocalSurfaceId. A new LSI had to be explicitly allocated before the
normal behavior could use it.

With ParentLocalSurfaceIdAllocator now default initializing a valid LSI,
the various call sites no longer need to explicitly check for the
uninitialized state.

LocalSurfaceIdProvider is one of those call sites.

BUG=837030

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: Ifec19249e74d2a705b54fec4d5d350ee435d87b0
Reviewed-on: https://chromium-review.googlesource.com/1036794
Commit-Queue: Chris Blume <cblume@chromium.org>
Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555218}

components/viz/client/local_surface_id_provider.cc

@@ -16,9 +16,7 @@ DefaultLocalSurfaceIdProvider::DefaultLocalSurfaceIdProvider() = default;
 
 const LocalSurfaceId& DefaultLocalSurfaceIdProvider::GetLocalSurfaceIdForFrame(
     const CompositorFrame& frame) {
-  if (!parent_local_surface_id_allocator_.GetCurrentLocalSurfaceId()
-           .is_valid() ||
-      surface_size_ != frame.size_in_pixels() ||
+  if (frame.size_in_pixels() != surface_size_ ||
       frame.device_scale_factor() != device_scale_factor_) {
     parent_local_surface_id_allocator_.GenerateId();
   }