Change remote-bound logs' retention on disk from 3 to 7 days

One motivation for this, is to avoid the last log captured on
a business day from expiring over the weekend, before it has
a chance to be uploaded.

Bug: 775415
Change-Id: I2f750b6c558e49f6a179f32f4a708fb5b997dbf2
Reviewed-on: https://chromium-review.googlesource.com/1096760Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Commit-Queue: Elad Alon <eladalon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566378}

chrome/browser/media/webrtc/webrtc_event_log_manager_remote.cc

@@ -104,7 +104,7 @@ static_assert(kMaxActiveRemoteBoundWebRtcEventLogs <=
               "This assumption affects unit test coverage.");
 
 const base::TimeDelta kRemoteBoundWebRtcEventLogsMaxRetention =
-    base::TimeDelta::FromDays(3);
+    base::TimeDelta::FromDays(7);
 
 const base::FilePath::CharType kRemoteBoundLogExtension[] =
     FILE_PATH_LITERAL("log");