Bug 1348053 - add the UrgentStart flag to the channel when the loading is initiated by a user interaction for quicker network response. r=cpearce

MozReview-Commit-ID: 1tk9k8u1zTu

dom/html/HTMLMediaElement.cpp

@@ -22,6 +22,7 @@
 #include "nsGenericHTMLElement.h"
 #include "nsAttrValueInlines.h"
 #include "nsPresContext.h"
+#include "nsIClassOfService.h"
 #include "nsIPresShell.h"
 #include "nsGkAtoms.h"
 #include "nsSize.h"
@@ -1159,6 +1160,12 @@ public:
       return;
     }
 
+    nsCOMPtr<nsIClassOfService> cos;
+    if (aElement->mUseUrgentStartForChannel &&
+        (cos = do_QueryInterface(channel))) {
+      cos->AddClassFlags(nsIClassOfService::UrgentStart);
+    }
+
     // The listener holds a strong reference to us.  This creates a
     // reference cycle, once we've set mChannel, which is manually broken
     // in the listener's OnStartRequest method after it is finished with
@@ -3891,6 +3898,14 @@ HTMLMediaElement::PlayInternal(ErrorResult& aRv)
   // Play was not blocked so assume user interacted with the element.
   mHasUserInteraction = true;
 
+  if (mPreloadAction == HTMLMediaElement::PRELOAD_NONE) {
+    // The media load algorithm will be initiated by a user interaction.
+    // We want to boost the channel priority for better responsiveness.
+    // Note this must be done before UpdatePreloadAction() which will
+    // update |mPreloadAction|.
+    mUseUrgentStartForChannel = true;
+  }
+
   StopSuspendingAfterFirstFrame();
   SetPlayedOrSeeked(true);