Download service: Rename DownloadService to BackgroundDownloadService.

Based on some discussion and to avoid class name conflicts, this CL
renames download::DownloadService to
download::BackgroundDownloadService.

Service factories and implementation classes are also renamed.

Trace event and histogram strings are not renamed.

Bug: 1215315
Change-Id: Ia65f680bc6a20e7ada37e3858f33eca16dc545f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2970207
Reviewed-by: Sophie Chang <[email protected]>
Reviewed-by: Carlos Knippschild <[email protected]>
Reviewed-by: Bo <[email protected]>
Reviewed-by: Alexander Alekseev <[email protected]>
Reviewed-by: Sylvain Defresne <[email protected]>
Reviewed-by: Peter Beverloo <[email protected]>
Reviewed-by: David Trainor <[email protected]>
Commit-Queue: Xing Liu <[email protected]>
Cr-Commit-Position: refs/heads/master@{#894342}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index f989f4f8..f5b3b0e 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -398,6 +398,8 @@
     "dom_distiller/tab_utils.h",
     "domain_reliability/service_factory.cc",
     "domain_reliability/service_factory.h",
+    "download/background_download_service_factory.cc",
+    "download/background_download_service_factory.h",
     "download/chrome_download_manager_delegate.cc",
     "download/chrome_download_manager_delegate.h",
     "download/deferred_client_wrapper.cc",
@@ -434,8 +436,6 @@
     "download/download_query.h",
     "download/download_request_limiter.cc",
     "download/download_request_limiter.h",
-    "download/download_service_factory.cc",
-    "download/download_service_factory.h",
     "download/download_started_animation.h",
     "download/download_stats.cc",
     "download/download_stats.h",