Add support for HTMLMediaElement::getStartDate()

public/platform/WebMediaPlayer.h

Index: public/platform/WebMediaPlayer.h
diff --git a/public/platform/WebMediaPlayer.h b/public/platform/WebMediaPlayer.h
index f329a926cbd2d1f578f8e096dd792256239171bb..ec110ef2c90e0b2c780b27a8402a003f0b5f0e90 100644
--- a/public/platform/WebMediaPlayer.h
+++ b/public/platform/WebMediaPlayer.h
@@ -36,6 +36,8 @@
 #include "WebString.h"
 #include "WebTimeRange.h"
 
+#include <limits>
+
 namespace blink {
 
 class WebAudioSourceProvider;
@@ -123,6 +125,15 @@ public:
     virtual bool paused() const = 0;
     virtual bool seeking() const = 0;
     virtual double duration() const = 0;
+
+    // Returns the 'timeline offset' as defined in the HTML5 spec
+    // (http://www.w3.org/html/wg/drafts/html/master/embedded-content.html#timeline-offset).
+    // The function should return the number of milliseconds between the
+    // 'timeline offset' and January 1, 1970 UTC. Use base::Time::ToJsTime() for

[philipj_slow, 2014/05/06 11:13:52]

s/for/to/

+    // generate this value from Chromium code. If the content does not have a
+    // 'timeline offset' then std::numeric_limits<double>::quiet_NaN() should be returned.
+    virtual double timelineOffset() const { return std::numeric_limits<double>::quiet_NaN(); }
+
     virtual double currentTime() const = 0;
 
     // Internal states of loading and network.