Cleanup some xfa/fxfa code.

This CL moves the .h files to have names corresponding to the contained
classes. The .cpp files are moved alongside the .h files. Any extra
classes in the .h files have been split into their own files.

Change-Id: I14b4efc02417f0df946500e87b6c502e77020db8
Reviewed-on: https://pdfium-review.googlesource.com/3160
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Nicolás Peña <npm@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_interform.cpp b/fpdfsdk/cpdfsdk_interform.cpp
index 1dbffa4..a16ec93 100644
--- a/fpdfsdk/cpdfsdk_interform.cpp
+++ b/fpdfsdk/cpdfsdk_interform.cpp
@@ -40,9 +40,9 @@
 #include "fpdfsdk/fpdfxfa/cpdfxfa_context.h"
 #include "fpdfsdk/fpdfxfa/cxfa_fwladaptertimermgr.h"
 #include "xfa/fxfa/cxfa_eventparam.h"
-#include "xfa/fxfa/xfa_ffdocview.h"
-#include "xfa/fxfa/xfa_ffwidget.h"
-#include "xfa/fxfa/xfa_ffwidgethandler.h"
+#include "xfa/fxfa/cxfa_ffdocview.h"
+#include "xfa/fxfa/cxfa_ffwidget.h"
+#include "xfa/fxfa/cxfa_ffwidgethandler.h"
 #endif  // PDF_ENABLE_XFA
 
 CPDFSDK_InterForm::CPDFSDK_InterForm(CPDFSDK_FormFillEnvironment* pFormFillEnv)