[Nearby] Handle clicking success notification body

If the body of a success notification is clicked, then the primary
action should be taken instead of doing nothing.

Fixed: 1168293
Change-Id: I494bcf53ec1bb1cd615a30e417c95e01877c9431
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2643856Reviewed-by: James Vecore <vecore@google.com>
Commit-Queue: Curt Clemens <cclem@google.com>
Cr-Commit-Position: refs/heads/master@{#846168}

chrome/browser/nearby_sharing/nearby_notification_manager.cc

@@ -376,20 +376,21 @@ class SuccessNotificationDelegate : public NearbyNotificationDelegate {
   // NearbyNotificationDelegate:
   void OnClick(const std::string& notification_id,
                const base::Optional<int>& action_index) override {
-    // Ignore clicks on notification body.
-    if (!action_index)
-      return;
-
     switch (type_) {
       case NearbyNotificationManager::ReceivedContentType::kText:
-        DCHECK_EQ(0, *action_index);
-        CopyTextToClipboard();
+        if (action_index.has_value() && action_index.value() == 0) {
+          // Don't overwrite clipboard if user clicks notification body
+          CopyTextToClipboard();
+        }
         break;
       case NearbyNotificationManager::ReceivedContentType::kSingleUrl:
-        DCHECK_EQ(0, *action_index);
         OpenTextLink();
         break;
       case NearbyNotificationManager::ReceivedContentType::kSingleImage:
+        if (!action_index.has_value()) {
+          OpenDownloadsFolder();
+          break;
+        }
         switch (*action_index) {
           case 0:
             OpenDownloadsFolder();
@@ -403,7 +404,6 @@ class SuccessNotificationDelegate : public NearbyNotificationDelegate {
         }
         break;
       case NearbyNotificationManager::ReceivedContentType::kFiles:
-        DCHECK_EQ(0, *action_index);
         OpenDownloadsFolder();
         break;
     }