Add 'autoplay' content settings and expose it to Blink.

chrome/renderer/content_settings_observer.cc

Index: chrome/renderer/content_settings_observer.cc
diff --git a/chrome/renderer/content_settings_observer.cc b/chrome/renderer/content_settings_observer.cc
index cebc683a55be25c53110620f4ef7446a1070c7dc..12e9750881d7c396d99cc7728c956e8be187477b 100644
--- a/chrome/renderer/content_settings_observer.cc
+++ b/chrome/renderer/content_settings_observer.cc
@@ -486,6 +486,18 @@ bool ContentSettingsObserver::allowRunningInsecureContent(
   return true;
 }
 
+bool ContentSettingsObserver::allowAutoplay(bool default_value) {
+  if (!content_setting_rules_)
+    return default_value;
+
+  WebFrame* frame = render_frame()->GetWebFrame();
+  return GetContentSettingFromRules(
+      content_setting_rules_->autoplay_rules,
+      frame,
+      blink::WebStringToGURL(frame->document().getSecurityOrigin().toString()))
+    == CONTENT_SETTING_ALLOW;
+}
+
 void ContentSettingsObserver::didUseKeygen() {
   WebFrame* frame = render_frame()->GetWebFrame();
   Send(new ChromeViewHostMsg_DidUseKeygen(