Create CastToolbarButton only if Media Router is enabled

The Cast icon should not be created if the Media Router feature is
disabled. The enabled state should not change during runtime.

Bug: 875868
Change-Id: I74c60e6549292d0ec139cfb9e29bf88de8fc66b1
Reviewed-on: https://chromium-review.googlesource.com/1181934Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Takumi Fujimoto <takumif@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584858}

chrome/browser/ui/views/toolbar/toolbar_view.cc

@@ -208,8 +208,10 @@ void ToolbarView::Init() {
       new BrowserActionsContainer(browser_, main_container, this);
 
   if (ui::MaterialDesignController::IsRefreshUi()) {
-    if (media_router::ShouldUseViewsDialog())
+    if (media_router::MediaRouterEnabled(browser_->profile()) &&
+        media_router::ShouldUseViewsDialog()) {
       cast_ = media_router::CastToolbarButton::Create(browser_).release();
+    }
 
     bool show_avatar_toolbar_button = true;
 #if defined(OS_CHROMEOS)