Bug 1380158: Use the aIID parameter supplied to mscom::ProxyStream's constructor to simplify and speed up proxy unmarshaling; r=jimm

MozReview-Commit-ID: 5YXpQXYGgjP

--HG--
extra : rebase_source : d6a8dbb524282f9365e055bc96879eeb4bbf78e3

ipc/mscom/COMPtrHolder.h

@@ -132,7 +132,7 @@ struct ParamTraits<mozilla::mscom::COMPtrHolder<Interface, _IID>>
     }
 
     typename paramType::COMPtrType ptr;
-    if (!proxyStream.GetInterface(_IID, mozilla::mscom::getter_AddRefs(ptr))) {
+    if (!proxyStream.GetInterface(mozilla::mscom::getter_AddRefs(ptr))) {
       return false;
     }
 

ipc/mscom/ProxyStream.cpp

@@ -62,7 +62,7 @@ ProxyStream::ProxyStream(REFIID aIID, const BYTE* aInitBuf,
     // OK to forget mStream when calling into this function because the stream
     // gets released even if the unmarshaling part fails.
     unmarshalResult =
-      ::CoGetInterfaceAndReleaseStream(mStream.forget().take(), IID_IUnknown,
+      ::CoGetInterfaceAndReleaseStream(mStream.forget().take(), aIID,
                                        getter_AddRefs(mUnmarshaledProxy));
     MOZ_ASSERT(SUCCEEDED(unmarshalResult));
   };
@@ -190,7 +190,7 @@ ProxyStream::GetBuffer(int& aReturnedBufSize) const
 }
 
 bool
-ProxyStream::GetInterface(REFIID aIID, void** aOutInterface) const
+ProxyStream::GetInterface(void** aOutInterface)
 {
   // We should not have a locked buffer on this side
   MOZ_ASSERT(!mGlobalLockedBuf);
@@ -200,26 +200,8 @@ ProxyStream::GetInterface(REFIID aIID, void** aOutInterface) const
     return false;
   }
 
-  if (!mUnmarshaledProxy) {
-    *aOutInterface = nullptr;
-    return true;
-  }
-
-  HRESULT hr = E_UNEXPECTED;
-
-  auto qiFn = [&]() -> void
-  {
-    hr = mUnmarshaledProxy->QueryInterface(aIID, aOutInterface);
-  };
-
-  if (XRE_IsParentProcess()) {
-    qiFn();
-  } else {
-    // mUnmarshaledProxy requires that we execute this in the MTA
-    EnsureMTA mta(qiFn);
-  }
-
-  return SUCCEEDED(hr);
+  *aOutInterface = mUnmarshaledProxy.release();
+  return true;
 }
 
 ProxyStream::ProxyStream(REFIID aIID, IUnknown* aObject)

ipc/mscom/ProxyStream.h

@@ -37,7 +37,7 @@ public:
     return !(mStream && mUnmarshaledProxy);
   }
 
-  bool GetInterface(REFIID aIID, void** aOutInterface) const;
+  bool GetInterface(void** aOutInterface);
   const BYTE* GetBuffer(int& aReturnedBufSize) const;
 
   bool operator==(const ProxyStream& aOther) const