4 files changed, 13 insertions, 12 deletions
diff --git a/netwerk/protocol/data/nsDataChannel.cpp b/netwerk/protocol/data/nsDataChannel.cpp
index 87b00adea3..df40971e1c 100644
--- a/netwerk/protocol/data/nsDataChannel.cpp
+++ b/netwerk/protocol/data/nsDataChannel.cpp
@@ -8,6 +8,7 @@
 #include "nsDataChannel.h"
 
 #include "mozilla/Base64.h"
+#include "mozilla/dom/MimeType.h"
 #include "nsDataHandler.h"
 #include "nsIInputStream.h"
 #include "nsEscape.h"
@@ -59,9 +60,10 @@ nsresult nsDataChannel::OpenContentStream(bool async, nsIInputStream** result,
 
   nsCString contentType, contentCharset;
   nsDependentCSubstring dataRange;
+  RefPtr<CMimeType> fullMimeType;
   bool lBase64;
   rv = nsDataHandler::ParsePathWithoutRef(path, contentType, &contentCharset,
-                                          lBase64, &dataRange, &mMimeType);
+                                          lBase64, &dataRange, &fullMimeType);
   if (NS_FAILED(rv)) return rv;
 
   // This will avoid a copy if nothing needs to be unescaped.
@@ -103,6 +105,7 @@ nsresult nsDataChannel::OpenContentStream(bool async, nsIInputStream** result,
 
   SetContentType(contentType);
   SetContentCharset(contentCharset);
+  SetFullMimeType(std::move(fullMimeType));
   mContentLength = contentLen;
 
   // notify "data-channel-opened" observers
diff --git a/netwerk/protocol/data/nsDataChannel.h b/netwerk/protocol/data/nsDataChannel.h
index d7313d66a0..f7700ff2b4 100644
--- a/netwerk/protocol/data/nsDataChannel.h
+++ b/netwerk/protocol/data/nsDataChannel.h
@@ -16,14 +16,10 @@ class nsDataChannel : public nsBaseChannel {
  public:
   explicit nsDataChannel(nsIURI* uri) { SetURI(uri); }
 
-  const nsACString& MimeType() const { return mMimeType; }
-
  protected:
   [[nodiscard]] virtual nsresult OpenContentStream(
       bool async, nsIInputStream** result, nsIChannel** channel) override;
 
-  nsCString mMimeType;
-
  private:
   nsresult MaybeSendDataChannelOpenNotification();
 };
diff --git a/netwerk/protocol/data/nsDataHandler.cpp b/netwerk/protocol/data/nsDataHandler.cpp
index d3a5743097..adb86bf484 100644
--- a/netwerk/protocol/data/nsDataHandler.cpp
+++ b/netwerk/protocol/data/nsDataHandler.cpp
@@ -161,7 +161,7 @@ nsresult nsDataHandler::ParsePathWithoutRef(const nsACString& aPath,
                                             nsCString* aContentCharset,
                                             bool& aIsBase64,
                                             nsDependentCSubstring* aDataBuffer,
-                                            nsCString* aMimeType) {
+                                            RefPtr<CMimeType>* aMimeType) {
   static constexpr auto kCharset = "charset"_ns;
 
   // This implements https://fetch.spec.whatwg.org/#data-url-processor
@@ -200,18 +200,18 @@ nsresult nsDataHandler::ParsePathWithoutRef(const nsACString& aPath,
   // This also checks for instances of ;base64 in the middle of the MimeType.
   // This is against the current spec, but we're doing it because we have
   // historically seen webcompat issues relying on this (see bug 781693).
-  if (mozilla::UniquePtr<CMimeType> parsed = CMimeType::Parse(mimeType)) {
+  if (RefPtr<CMimeType> parsed = CMimeType::Parse(mimeType)) {
     parsed->GetEssence(aContentType);
     if (aContentCharset) {
       parsed->GetParameterValue(kCharset, *aContentCharset);
     }
-    if (aMimeType) {
-      parsed->Serialize(*aMimeType);
-    }
     if (parsed->IsBase64() &&
         !StaticPrefs::network_url_strict_data_url_base64_placement()) {
       aIsBase64 = true;
     }
+    if (aMimeType) {
+      *aMimeType = std::move(parsed);
+    }
   } else {
     // "If mimeTypeRecord is failure, then set mimeTypeRecord to
     // text/plain;charset=US-ASCII."
@@ -220,7 +220,8 @@ nsresult nsDataHandler::ParsePathWithoutRef(const nsACString& aPath,
       aContentCharset->AssignLiteral("US-ASCII");
     }
     if (aMimeType) {
-      aMimeType->AssignLiteral("text/plain;charset=US-ASCII");
+      *aMimeType = new CMimeType("text"_ns, "plain"_ns);
+      (*aMimeType)->SetParameterValue("charset"_ns, "US-ASCII"_ns);
     }
   }
 
diff --git a/netwerk/protocol/data/nsDataHandler.h b/netwerk/protocol/data/nsDataHandler.h
index 4796f0f453..499e73b220 100644
--- a/netwerk/protocol/data/nsDataHandler.h
+++ b/netwerk/protocol/data/nsDataHandler.h
@@ -6,6 +6,7 @@
 #ifndef nsDataHandler_h___
 #define nsDataHandler_h___
 
+#include "mozilla/dom/MimeType.h"
 #include "nsIProtocolHandler.h"
 #include "nsWeakReference.h"
 
@@ -50,7 +51,7 @@ class nsDataHandler : public nsIProtocolHandler,
   [[nodiscard]] static nsresult ParsePathWithoutRef(
       const nsACString& aPath, nsCString& aContentType,
       nsCString* aContentCharset, bool& aIsBase64,
-      nsDependentCSubstring* aDataBuffer, nsCString* aMimeType = nullptr);
+      nsDependentCSubstring* aDataBuffer, RefPtr<CMimeType>* = nullptr);
 };
 
 #endif /* nsDataHandler_h___ */