Bug 1490235 - Use nsDependentCSubstring in AltDataOutputStreamChild::WriteDataInChunks r=mayhemer

Simply replace the nsCString with nsDependentCSubstring to avoid copying the data. In this way, we can also avoid the potential OOM crash.

Differential Revision: https://phabricator.services.mozilla.com/D6685

--HG--
extra : moz-landing-system : lando

netwerk/protocol/http/AltDataOutputStreamChild.cpp

@@ -59,7 +59,7 @@ AltDataOutputStreamChild::ReleaseIPDLReference()
 }
 
 bool
-AltDataOutputStreamChild::WriteDataInChunks(const nsCString& data)
+AltDataOutputStreamChild::WriteDataInChunks(const nsDependentCSubstring& data)
 {
   const uint32_t kChunkSize = 128*1024;
   uint32_t next = std::min(data.Length(), kChunkSize);
@@ -110,7 +110,7 @@ AltDataOutputStreamChild::Write(const char * aBuf, uint32_t aCount, uint32_t *_r
   if (NS_FAILED(mError)) {
     return mError;
   }
-  if (WriteDataInChunks(nsCString(aBuf, aCount))) {
+  if (WriteDataInChunks(nsDependentCSubstring(aBuf, aCount))) {
     *_retval = aCount;
     return NS_OK;
   }

netwerk/protocol/http/AltDataOutputStreamChild.h

@@ -32,7 +32,7 @@ public:
 private:
   virtual ~AltDataOutputStreamChild() = default;
   // Sends data to the parent process in 256k chunks.
-  bool WriteDataInChunks(const nsCString& data);
+  bool WriteDataInChunks(const nsDependentCSubstring& data);
 
   bool mIPCOpen;
   // If there was an error opening the output stream or writing to it on the