Cache Storage: Move files to content/*/cache_storage, rename classes

content/browser/cache_storage/BUILD.gn

Index: content/browser/cache_storage/BUILD.gn
diff --git a/content/browser/background_sync/BUILD.gn b/content/browser/cache_storage/BUILD.gn
similarity index 77%
copy from content/browser/background_sync/BUILD.gn
copy to content/browser/cache_storage/BUILD.gn
index 55aeded7a53a4379bfa84619a1796410c1e7a0fa..7b33ea105f1e3b08e65cf7dbb2ebdbfb4b9438a2 100644
--- a/content/browser/background_sync/BUILD.gn
+++ b/content/browser/cache_storage/BUILD.gn
@@ -4,8 +4,8 @@
 
 import("//third_party/protobuf/proto_library.gni")
 
-proto_library("background_sync_proto") {
+proto_library("cache_storage_proto") {
   sources = [
-    "background_sync.proto",
+    "cache_storage.proto",
   ]
 }