Bug 1194891. P4 - close all streams associated with private browsing windows when PB is done. r=cpearce

MozReview-Commit-ID: MmvMuzuFX3

--HG--
extra : rebase_source : d5f98bd815323e9a79959af49a9585d8f6108d28
extra : source : 7a82be361a50b950b579a5f6b1872d10de80d76f

dom/media/MediaCache.cpp

@@ -140,6 +140,11 @@ public:
   static void Flush();
   void FlushInternal();
 
+  // Close all streams associated with private browsing windows. This will
+  // also remove the blocks from the cache since we don't want to leave any
+  // traces when PB is done.
+  static void CloseStreamsForPrivateBrowsing();
+
   // Cache-file access methods. These are the lowest-level cache methods.
   // mReentrantMonitor must be held; these can be called on any thread.
   // This can return partial reads.
@@ -355,10 +360,12 @@ NS_IMETHODIMP
 MediaCacheFlusher::Observe(nsISupports *aSubject, char const *aTopic, char16_t const *aData)
 {
   if (strcmp(aTopic, "last-pb-context-exited") == 0) {
-    MediaCache::Flush();
+    MediaCache::CloseStreamsForPrivateBrowsing();
+    return NS_OK;
   }
   if (strcmp(aTopic, "cacheservice:empty-cache") == 0) {
     MediaCache::Flush();
+    return NS_OK;
   }
   return NS_OK;
 }
@@ -614,6 +621,20 @@ MediaCache::FlushInternal()
   Init();
 }
 
+void
+MediaCache::CloseStreamsForPrivateBrowsing()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!gMediaCache) {
+    return;
+  }
+  for (auto& s : gMediaCache->mStreams) {
+    if (s->mIsPrivateBrowsing) {
+      s->Close();
+    }
+  }
+}
+
 void
 MediaCache::MaybeShutdown()
 {