Expose a seekable range at 0 for streaming sources with duration.

media/blink/webmediaplayer_impl.cc

Index: media/blink/webmediaplayer_impl.cc
diff --git a/media/blink/webmediaplayer_impl.cc b/media/blink/webmediaplayer_impl.cc
index cd80f3ab4a568cb32eb59f4aedf8b0bdb818135d..68fab8b311e55ca2cfa925d6c1df188c635a9e0b 100644
--- a/media/blink/webmediaplayer_impl.cc
+++ b/media/blink/webmediaplayer_impl.cc
@@ -15,6 +15,7 @@
 #include "base/debug/alias.h"
 #include "base/debug/crash_logging.h"
 #include "base/debug/trace_event.h"
+#include "base/float_util.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/metrics/histogram.h"
 #include "base/single_thread_task_runner.h"
@@ -492,14 +493,14 @@ blink::WebTimeRanges WebMediaPlayerImpl::seekable() const {
   if (ready_state_ < WebMediaPlayer::ReadyStateHaveMetadata)
     return blink::WebTimeRanges();
 
-  // We don't support seeking in streaming media.
-  if (data_source_ && data_source_->IsStreaming())
-    return blink::WebTimeRanges();
-
-  // If we have a duration then use [0, duration] as the seekable range.
-  const double seekable_end = duration();
-  if (!seekable_end)
-    return blink::WebTimeRanges();
+  // We don't support seeking in streaming media except for a seek to zero when
+  // the source has a known duration.
+  double seekable_end = duration();
+  if (data_source_ && data_source_->IsStreaming()) {

[philipj_slow, 2014/10/01 09:37:50]

Can you DCHECK(base::IsFinite(seekable_end) && seekable_end > 0.0) in an else
branch, or does that not always hold true? The previous code clearly never
returned a [0,0] range, but now it's not clear if it's possible for the
non-streaming case or not.

[DaleCurtis, 2014/10/06 23:55:42]

I've reworked this to look more like the android code. !IsFinite(duration) will
always return an empty range now.  Streaming media will return 0,0.

+    if (!base::IsFinite(seekable_end))
+      return blink::WebTimeRanges();
+    seekable_end = 0.0;
+  }
 
   blink::WebTimeRange seekable_range(0.0, seekable_end);
   return blink::WebTimeRanges(&seekable_range, 1);