Clear device labels from MediaStreamTrack.getSources() if not authorized

This CL queries the content settings to see if getSources() is authorized
to fill in SourceInfo.label, and if not, clears the values before they are
sent to the renderer process.

BUG=240710

Review URL: https://chromiumcodereview.appspot.com/20848002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@215991 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/content/shell/shell_browser_context.cc b/content/shell/shell_browser_context.cc
index 58b966c..1c893550 100644
--- a/content/shell/shell_browser_context.cc
+++ b/content/shell/shell_browser_context.cc
@@ -43,6 +43,12 @@
     CHECK(getter_);
     return getter_->GetURLRequestContext();
   }
+  virtual bool AllowMicAccess(const GURL& origin) OVERRIDE {
+    return false;
+  }
+  virtual bool AllowCameraAccess(const GURL& origin) OVERRIDE {
+    return false;
+  }
 
   void set_url_request_context_getter(ShellURLRequestContextGetter* getter) {
     getter_ = getter;