content: Cleanup class/struct forward declarations

content/public/browser/web_contents_delegate.h

Index: content/public/browser/web_contents_delegate.h
diff --git a/content/public/browser/web_contents_delegate.h b/content/public/browser/web_contents_delegate.h
index 7ae96adf496a6b25c585b164e43cd55bb3bfe9ae..19a14dd53f50f3be95ac97825992336df9fe3ecc 100644
--- a/content/public/browser/web_contents_delegate.h
+++ b/content/public/browser/web_contents_delegate.h
@@ -38,9 +38,7 @@ class ListValue;
 }
 
 namespace content {
-class BrowserContext;
 class ColorChooser;
-class DownloadItem;
 class JavaScriptDialogManager;
 class PageState;
 class RenderFrameHost;
@@ -54,7 +52,6 @@ struct FileChooserParams;
 struct NativeWebKeyboardEvent;
 struct Referrer;
 struct SecurityStyleExplanations;
-struct SSLStatus;
 }  // namespace content
 
 namespace gfx {
@@ -67,10 +64,6 @@ namespace net {
 class X509Certificate;
 }
 
-namespace url {
-class Origin;
-}
-
 namespace blink {
 class WebGestureEvent;
 }