Finish removing redundant methods on BrowserContext.

The media URLRequestContext should be retrieved from the storage partition, not the browser context.

BUG=159193

Review URL: https://codereview.chromium.org/1892893002

Cr-Commit-Position: refs/heads/master@{#387687}
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 306adc50..4802c80 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -3369,8 +3369,8 @@
   if (url.is_valid() && url.SchemeIsHTTPOrHTTPS()) {
     scoped_refptr<net::URLRequestContextGetter> request_context(
         resource_type == RESOURCE_TYPE_MEDIA ?
-            GetBrowserContext()->GetMediaRequestContextForRenderProcess(
-                GetRenderProcessHost()->GetID()) :
+            GetRenderProcessHost()->GetStoragePartition()->
+                GetMediaURLRequestContext() :
             GetRenderProcessHost()->GetStoragePartition()->
                 GetURLRequestContext());
     BrowserThread::PostTask(