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

media/blink/webmediaplayer_impl.cc

 // Copyright 2013 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 "media/blink/webmediaplayer_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #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"
 #include "base/synchronization/waitable_event.h"
 #include "cc/blink/web_layer_impl.h"
 #include "cc/layers/video_layer.h"
 #include "gpu/GLES2/gl2extchromium.h"
 #include "gpu/command_buffer/common/mailbox_holder.h"
 #include "media/audio/null_audio_sink.h"
 #include "media/base/audio_hardware_config.h"
@@ skipping 457 matching lines @@
 }
 
 blink::WebTimeRanges WebMediaPlayerImpl::seekable() const {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
 
   // If we haven't even gotten to ReadyStateHaveMetadata yet then there
   // are no seekable ranges.
   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);
 }
 
 bool WebMediaPlayerImpl::didLoadingProgress() {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
   bool pipeline_progress = pipeline_.DidLoadingProgress();
   bool data_progress = buffered_data_source_host_.DidLoadingProgress();
   return pipeline_progress || data_progress;
@@ skipping 516 matching lines @@
   compositor_task_runner_->PostTask(FROM_HERE,
                                     base::Bind(&GetCurrentFrameAndSignal,
                                                base::Unretained(compositor_),
                                                &video_frame,
                                                &event));
   event.Wait();
   return video_frame;
 }
 
 }  // namespace media