Converts Android-specific cookie accesses to Mojo.

Converts all instances of access to net::CookieStore over to
network::mojom::CookieManager.

Addressed the uses of cookie store in the following android-specific files:
  - content/browser/media/android

This is a follow-up CL to #903307.

Bug: 792672
Change-Id: Ifb5ee30dfb746e66aa4c06674abb8e9e22ec1d1b
Reviewed-on: https://chromium-review.googlesource.com/952954Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Pritam Nikam <pritam.nikam@samsung.com>
Cr-Commit-Position: refs/heads/master@{#543297}

content/browser/media/android/media_resource_getter_impl.h

@@ -63,10 +63,6 @@ class MediaResourceGetterImpl : public media::MediaResourceGetter {
   void GetAuthCredentialsCallback(GetAuthCredentialsCB callback,
                                   const net::AuthCredentials& credentials);
 
-  // Called when GetCookies() finishes.
-  void GetCookiesCallback(GetCookieCB callback,
-                          const net::CookieList& cookie_list);
-
   // Called when GetPlatformPathFromFileSystemURL() finishes.
   void GetPlatformPathCallback(GetPlatformPathCB callback,
                                const std::string& platform_path);