Propagate audible state from player to the containing tab

content/browser/media/audio_state_provider.cc

+#include "content/browser/media/audio_state_provider.h"
+
+#include "base/logging.h"
+#include "content/browser/media/audio_stream_monitor.h"
+#include "content/public/browser/web_contents.h"
+
+namespace content {
+
+AudioStateProvider::AudioStateProvider(WebContents* contents)
+    : web_contents_(contents),
+      was_recently_audible_(false) {
+  DCHECK(web_contents_);
+}
+
+
+// static
+bool AudioStateProvider::audio_state_available() {
+#if defined OS_ANDROID
+  return true;
+#else
+  return AudioStreamMonitor::monitoring_available();
+#endif // !defined OS_ANDROID
+}
+
+bool AudioStateProvider::WasRecentlyAudible() const {
+  return was_recently_audible_;
+}
+
+void AudioStateProvider::Notify(bool new_state) {
+  if (was_recently_audible_ != new_state) {
+    was_recently_audible_ = new_state;
+    web_contents_->NotifyNavigationStateChanged(INVALIDATE_TYPE_TAB);
+  }
+}
+
+} // namespace content