[Nearby] Separate Get/GetOrCreate for ShareTargetInfo

This adds Get/GetOrCreate methods for ShareTargetInfo so we don't
accidentally create entries in the maps. Only a few places actually
need to create a new entry and this makes it easier to track those.

Bug: 1085067
Change-Id: I3d9f20a9a371a0af3968a485748d611840e299b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2353334Reviewed-by: Himanshu Jaju <himanshujaju@chromium.org>
Commit-Queue: Richard Knoll <knollr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800125}

chrome/browser/nearby_sharing/nearby_sharing_service_impl.h

@@ -211,12 +211,17 @@ class NearbySharingServiceImpl
       base::Optional<NearbyShareDecryptedPublicCertificate> certificate,
       bool is_incoming);
 
-  IncomingShareTargetInfo& GetIncomingShareTargetInfo(
+  ShareTargetInfo& GetOrCreateShareTargetInfo(const ShareTarget& share_target,
+                                              const std::string& endpoint_id);
+
+  ShareTargetInfo* GetShareTargetInfo(const ShareTarget& share_target);
+  IncomingShareTargetInfo* GetIncomingShareTargetInfo(
+      const ShareTarget& share_target);
+  OutgoingShareTargetInfo* GetOutgoingShareTargetInfo(
       const ShareTarget& share_target);
-  NearbyConnection* GetIncomingConnection(const ShareTarget& share_target);
-  OutgoingShareTargetInfo& GetOrCreateOutgoingShareTargetInfo(
-      const ShareTarget& share_target,
-      const std::string& endpoint_id);
+
+  NearbyConnection* GetConnection(const ShareTarget& share_target);
+
   void ClearOutgoingShareTargetInfoMap();
   void SetAttachmentPayloadId(const Attachment& attachment, int64_t payload_id);
   base::Optional<int64_t> GetAttachmentPayloadId(int64_t attachment_id);