LocalSurfaceIdProvider to use allocator's copy

The LSI allocators previously did not store a copy of the last generated
LSI. As a result, many call sites would have to keep their own copies.

Now that the LSI allocators have their own copies, the call sites can be
updated to no longer store a separate copy.

LocalSurfaceIdProvider is one such call site.

BUG=759031

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: I85aad90edc9d61ae1c2924d3bbc5fc92b3b9376b
Reviewed-on: https://chromium-review.googlesource.com/1005801Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Commit-Queue: Fady Samuel <fsamuel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549647}

components/viz/client/local_surface_id_provider.cc

@@ -16,14 +16,15 @@ DefaultLocalSurfaceIdProvider::DefaultLocalSurfaceIdProvider() = default;
 
 const LocalSurfaceId& DefaultLocalSurfaceIdProvider::GetLocalSurfaceIdForFrame(
     const CompositorFrame& frame) {
-  if (!local_surface_id_.is_valid() ||
+  if (!parent_local_surface_id_allocator_.GetCurrentLocalSurfaceId()
+           .is_valid() ||
       surface_size_ != frame.size_in_pixels() ||
       frame.device_scale_factor() != device_scale_factor_) {
-    local_surface_id_ = parent_local_surface_id_allocator_.GenerateId();
+    parent_local_surface_id_allocator_.GenerateId();
   }
   surface_size_ = frame.size_in_pixels();
   device_scale_factor_ = frame.device_scale_factor();
-  return local_surface_id_;
+  return parent_local_surface_id_allocator_.GetCurrentLocalSurfaceId();
 }
 
 }  // namespace viz

components/viz/client/local_surface_id_provider.h

@@ -34,7 +34,6 @@ class VIZ_CLIENT_EXPORT DefaultLocalSurfaceIdProvider
       const CompositorFrame& frame) override;
 
  private:
-  LocalSurfaceId local_surface_id_;
   gfx::Size surface_size_;
   float device_scale_factor_ = 0;
   ParentLocalSurfaceIdAllocator parent_local_surface_id_allocator_;