Replace operator with lambda (content/browser)

When building with jumbo the compiler sees two
operator==, declared in the files:
content/common/media/media_devices.h
content/browser/indexed_db/scopes/scopes_lock_manager.cc

Therefore, it throws an error. This commit solves the
issue by replacing the operator with a lamdba doing
the same operation.

Change-Id: I285a95a77ac55d2502d146316da12339de277fc9
Reviewed-on: https://chromium-review.googlesource.com/1169468
Commit-Queue: Oscar Johansson <oscarj@opera.com>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582086}

content/browser/renderer_host/media/media_devices_manager.cc

@@ -829,7 +829,10 @@ void MediaDevicesManager::UpdateSnapshot(
   if (old_snapshot.size() != new_snapshot.size() ||
       !std::equal(new_snapshot.begin(), new_snapshot.end(),
                   old_snapshot.begin(),
-                  ignore_group_id ? operator== : EqualDeviceAndGroupID)) {
+                  ignore_group_id
+                      ? [](const MediaDeviceInfo& lhs,
+                           const MediaDeviceInfo& rhs) { return lhs == rhs; }
+                      : EqualDeviceAndGroupID)) {
     // Prevent sending notifications until group IDs are updated using
     // a heuristic in ProcessRequests().
     // TODO(crbug.com/627793): Remove |is_video_with_group_ids| and the