Implementing preload=metadata for video

media/base/filters.h

Index: media/base/filters.h
diff --git a/media/base/filters.h b/media/base/filters.h
index d6b962d64bb4775857662f3bbb62059ba10326a2..67a246bad3b30298e86f41cbb3b139d3c00b6ac6 100644
--- a/media/base/filters.h
+++ b/media/base/filters.h
@@ -43,6 +43,18 @@ class FilterHost;
 
 struct PipelineStatistics;
 
+// Used to specify video preload states. They are "hints" to the browser about
+// how aggressively the browser should load and buffer data.
+// Please see the HTML5 spec for the descriptions of these values:
+// http://www.w3.org/TR/html5/video.html#attr-media-preload
+//
+// Enum values must match the values in WebCore::MediaPlayer::Preload.
+enum Preload {
+  PRELOAD_NONE,

[acolwell GONE FROM CHROMIUM, 2011/03/29 05:52:03]

nit: How about dropping the PRELOAD_ prefix now that your comments got me
thinking about this. We should probably keep it MACRO_STYLE here since the other
enums in here are in that style.

[vrk (LEFT CHROMIUM), 2011/03/30 17:41:44]

Done.

+  PRELOAD_METADATA,
+  PRELOAD_AUTO,
+};
+
 // Used for completing asynchronous methods.
 typedef Callback0::Type FilterCallback;
 
@@ -127,6 +139,9 @@ class DataSource : public Filter {
   // Returns true if we are performing streaming. In this case seeking is
   // not possible.
   virtual bool IsStreaming() = 0;
+
+  // Alert the DataSource that the video preload value has been changed.
+  virtual void SetPreload(Preload preload) = 0;
 };
 
 class DemuxerStream : public base::RefCountedThreadSafe<DemuxerStream> {
@@ -180,6 +195,9 @@ class Demuxer : public Filter {
  public:
   // Returns the given stream type, or NULL if that type is not present.
   virtual scoped_refptr<DemuxerStream> GetStream(DemuxerStream::Type type) = 0;
+
+  // Alert the Demuxer that the video preload value has been changed.
+  virtual void SetPreload(Preload preload) = 0;
 };