[cdm]Enable Widevine on chromecast desktop build

Created functions to register cdm paths in cast_content_client.
Moved shared files into common directory.

Bug: b/145700375
Change-Id: I56b33b34393190e43b19d82a3e6143659ddbdb56
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2428729
Commit-Queue: Jimmy Xu <jimmyxu@google.com>
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Joshua Pawlicki <waffles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#863623}

diff --git a/chromecast/common/DEPS b/chromecast/common/DEPS
index b226070..3f1ef85 100644
--- a/chromecast/common/DEPS
+++ b/chromecast/common/DEPS

@@ -1,4 +1,5 @@
 include_rules = [
+  "+components/cdm/common",
   "+components/services/heap_profiling/public/cpp",
   "+components/url_matcher",
   "+components/version_info",
@@ -7,6 +8,7 @@
   "+extensions/grit",
   "+extensions/shell/common/api",
   "+extensions/shell/grit",
+  "+media",
   "+mojo/public/cpp/bindings",
   "+net/base",
   "+net/http",