Use noexcept consistently on media::learning::Instance ctor

Change-Id: I70abcd04649b4f91cba16ff364a61378e6ac0f0f
Reviewed-on: https://chromium-review.googlesource.com/c/1291189Reviewed-by: Frank Liberato <liberato@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601865}

media/learning/instance.cc

@@ -9,7 +9,7 @@ namespace learning {
 
 Instance::Instance() = default;
 Instance::~Instance() = default;
-Instance::Instance(Instance&& rhs) {
+Instance::Instance(Instance&& rhs) noexcept {
   features = std::move(rhs.features);
 }