Add options for audio/video autoplay to chrome://settings/content.

chrome/renderer/content_settings_observer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/content_settings_observer.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "components/content_settings/content/common/content_settings_messages.h"
 #include "content/public/common/url_constants.h"
@@ skipping 331 matching lines @@
       frame->top()->securityOrigin().isUnique())
     return false;
 
   bool result = false;
   Send(new ChromeViewHostMsg_AllowIndexedDB(
       routing_id(), GURL(frame->securityOrigin().toString()),
       GURL(frame->top()->securityOrigin().toString()), name, &result));
   return result;
 }
 
+bool ContentSettingsObserver::allowMediaAutoplay(bool hidden) {
+  if (!content_setting_rules_)
+    return true;
+
+  WebFrame* frame = render_frame()->GetWebFrame();
+  const ContentSetting setting = GetContentSettingFromRules(
+      content_setting_rules_->media_autoplay_rules, frame,
+      GURL(frame->document().securityOrigin().toString()));
+
+  return setting == CONTENT_SETTING_ALLOW ||
+         (setting == CONTENT_SETTING_DETECT_IMPORTANT_CONTENT && !hidden);

[philipj_slow, 2015/10/23 12:17:30]

Oh... so "important content" actually means anything in an open tab?

[DaleCurtis, 2015/10/23 19:21:27]

Currently and as planned yes. There are discussion to see if the plugin power
saver heuristics could be used: 

https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/p...

+}
+
 bool ContentSettingsObserver::allowPlugins(bool enabled_per_settings) {
   return enabled_per_settings;
 }
 
 bool ContentSettingsObserver::allowScript(bool enabled_per_settings) {
   if (!enabled_per_settings)
     return false;
   if (is_interstitial_page_)
     return true;
 
@@ skipping 362 matching lines @@
 
   // If the scheme is file:, an empty file name indicates a directory listing,
   // which requires JavaScript to function properly.
   if (base::EqualsASCII(protocol, url::kFileScheme)) {
     return document_url.SchemeIs(url::kFileScheme) &&
            document_url.ExtractFileName().empty();
   }
 
   return false;
 }