Merge to XFA: Rename CPDF_PageContentGenerate to CPDF_PageContentGenerator.

Original Review URL: https://codereview.chromium.org/1611193003 .
(cherry picked from commit ca6d98f4dfe7d4fc506b72c91f122f471a53c878)

R=ochang@chromium.org
TBR=ochang@chromium.org

Review URL: https://codereview.chromium.org/1613163003 .
diff --git a/fpdfsdk/src/fpdfeditpage.cpp b/fpdfsdk/src/fpdfeditpage.cpp
index c6d579a..650b626 100644
--- a/fpdfsdk/src/fpdfeditpage.cpp
+++ b/fpdfsdk/src/fpdfeditpage.cpp
@@ -242,7 +242,7 @@
           "Page")) {
     return FALSE;
   }
-  CPDF_PageContentGenerate CG(pPage);
+  CPDF_PageContentGenerator CG(pPage);
   CG.GenerateContent();
 
   return TRUE;