Mojoify WebContentSettingsClient for shared worker.

This patch Mojoifies WebContentSettingsClient used by shared worker.
SharedWorkerContentSettingsProxy is created in browser, and then passed onto 
renderer.
Inside blink, it gets some content settings information from browser 
via mojom::SharedWorkerContentSettingsProxy.

Replaced by SharedWorkerContentSettingsProxy,
EmbeddedSharedWorkerContentSettingsClientProxy was removed.

There are no useful tests for indexeddb or filesystem, so I tested this patch
by hand, Using some .js and called indexeddb.open and webkitRequestFileSystem.
https://crbug.com/113738 is for adding indexeddb tests, and it is still available.

Bug: 739092
Change-Id: I5523b3ba533707416452a56c5f04250a1117ba15
Reviewed-on: https://chromium-review.googlesource.com/562854
Reviewed-by: Makoto Shimazu <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Reviewed-by: Kinuko Yasuda <[email protected]>
Reviewed-by: Mike West <[email protected]>
Reviewed-by: Hiroki Nakagawa <[email protected]>
Reviewed-by: Matt Falkenhagen <[email protected]>
Commit-Queue: Yuki Yamada <[email protected]>
Cr-Commit-Position: refs/heads/master@{#490717}
diff --git a/content/browser/BUILD.gn b/content/browser/BUILD.gn
index 1402d86..82c330ec 100644
--- a/content/browser/BUILD.gn
+++ b/content/browser/BUILD.gn
@@ -1453,6 +1453,8 @@
     "service_worker/service_worker_version.h",
     "service_worker/service_worker_write_to_cache_job.cc",
     "service_worker/service_worker_write_to_cache_job.h",
+    "shared_worker/shared_worker_content_settings_proxy_impl.cc",
+    "shared_worker/shared_worker_content_settings_proxy_impl.h",
     "shared_worker/shared_worker_host.cc",
     "shared_worker/shared_worker_host.h",
     "shared_worker/shared_worker_instance.cc",