Increase default buffer size for wxWebRequest operations

Use 64KiB rather than 8KiB, as the latter seems rather small nowadays.

Also add a symbolic constant for this number.

include/wx/private/webrequest.h

@@ -18,6 +18,9 @@
 
 WX_DECLARE_STRING_HASH_MAP(wxString, wxWebRequestHeaderMap);
 
+// Default buffer size when a fixed-size buffer must be used.
+const int wxWEBREQUEST_BUFFER_SIZE = 64 * 1024;
+
 // ----------------------------------------------------------------------------
 // wxWebAuthChallengeImpl
 // ----------------------------------------------------------------------------

src/common/webrequest.cpp

@@ -509,7 +509,7 @@ wxWebAuthChallenge::SetCredentials(const wxWebCredentials& cred)
 
 wxWebResponseImpl::wxWebResponseImpl(wxWebRequestImpl& request) :
     m_request(request),
-    m_readSize(8 * 1024)
+    m_readSize(wxWEBREQUEST_BUFFER_SIZE)
 {
 }
 

src/msw/webrequest_winhttp.cpp

@@ -194,7 +194,7 @@ wxWebRequestWinHTTP::HandleCallback(DWORD dwInternetStatus,
 
 void wxWebRequestWinHTTP::WriteData()
 {
-    int dataWriteSize = 8 * 1024;
+    int dataWriteSize = wxWEBREQUEST_BUFFER_SIZE;
     if ( m_dataWritten + dataWriteSize > m_dataSize )
         dataWriteSize = m_dataSize - m_dataWritten;
     if ( !dataWriteSize )