mac: Make media router permission dialog work.

The mac implementation was hidden behind `defined(MAC_VIEWS_BROWSER)`
instead of `BUILDFLAG(MAC_VIEWS_BROWSER)` and hence was never enabled.

Since BUILDFLAG(MAC_VIEWS_BROWSER) is now always true, just remove
the check.

Bug: 849020
Change-Id: Ib4e9217304363d2d6e5ace4f1d44271ed6de1bfe
Reviewed-on: https://chromium-review.googlesource.com/c/1258027Reviewed-by: Takumi Fujimoto <takumif@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596078}

chrome/browser/media/cast_remoting_connector.cc

@@ -25,8 +25,7 @@
 #include "content/public/browser/web_contents.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
 
-#if defined(TOOLKIT_VIEWS) && \
-    (!defined(OS_MACOSX) || defined(MAC_VIEWS_BROWSER))
+#if defined(TOOLKIT_VIEWS)
 #include "chrome/browser/ui/views/media_router/media_remoting_dialog_view.h"
 #endif
 
@@ -139,8 +138,7 @@ CastRemotingConnector* CastRemotingConnector::Get(
         media_router::MediaRouterFactory::GetApiForBrowserContext(
             contents->GetBrowserContext()),
         SessionTabHelper::IdForTab(contents),
-#if defined(TOOLKIT_VIEWS) && \
-    (!defined(OS_MACOSX) || defined(MAC_VIEWS_BROWSER))
+#if defined(TOOLKIT_VIEWS)
         base::BindRepeating(
             [](content::WebContents* contents,
                PermissionResultCallback result_callback) {