Tweak multibuffer buffering strategy.

media/blink/multibuffer_data_source.cc

Index: media/blink/multibuffer_data_source.cc
diff --git a/media/blink/multibuffer_data_source.cc b/media/blink/multibuffer_data_source.cc
index 4abd3d8d157a1b87e0ce6b5dc01ad3375c8e9beb..43d1dd31ead4664275acc36be40cbea904f03b0f 100644
--- a/media/blink/multibuffer_data_source.cc
+++ b/media/blink/multibuffer_data_source.cc
@@ -567,16 +567,20 @@ void MultibufferDataSource::UpdateBufferSizes() {
 
   int64_t preload = clamp(kTargetSecondsBufferedAhead * bytes_per_second,
                           kMinBufferPreload, kMaxBufferPreload);
+  int64_t preload_high = preload + kPreloadHighExtra;
   int64_t back_buffer = clamp(kTargetSecondsBufferedBehind * bytes_per_second,
-                              kMinBufferPreload, kMaxBufferPreload);
-  int64_t pin_forwards = kMaxBufferSize - back_buffer;
-  DCHECK_LE(preload + kPreloadHighExtra, pin_forwards);
-  reader_->SetMaxBuffer(back_buffer, preload + kPreloadHighExtra);
+                              kMinBufferPreload, kMaxBufferSize - preload_high);

[DaleCurtis, 2016/05/04 21:39:32]

Seems like the subtraction could go negative?

[hubbe, 2016/05/04 21:55:06]

Adding a static assert to make sure it cannot.

+  int64_t buffer_size =
+      std::min((kTargetSecondsBufferedAhead + kTargetSecondsBufferedBehind) *
+                   bytes_per_second,
+               kMaxBufferSize);
+  reader_->SetMaxBuffer(buffer_size);
+  reader_->SetPinRange(back_buffer, kMaxBufferPreload);
 
   if (preload_ == METADATA) {
     reader_->SetPreload(0, 0);
   } else {
-    reader_->SetPreload(preload + kPreloadHighExtra, preload);
+    reader_->SetPreload(preload_high, preload);
   }
 }