Simplify PDFium by removing code that's not used in the open source repo.

pdfium.gyp

Index: pdfium.gyp
diff --git a/pdfium.gyp b/pdfium.gyp
index 7e7dba9dfc56c58b82ccf796529446de5be82cdd..6b4b8bcea5353d1060da12f3cd01d10dd432c531 100644
--- a/pdfium.gyp
+++ b/pdfium.gyp
@@ -4,7 +4,6 @@
   },
   'target_defaults': {
     'defines' : [
-      'FOXIT_CHROME_BUILD',
       '_FXFT_VERSION_=2501',
       '_FPDFSDK_LIB',
       '_NO_GDIPLUS_',  # workaround text rendering issues on Windows
@@ -55,7 +54,6 @@
         'fpdfsdk/include/fpdfdoc.h',
         'fpdfsdk/include/fpdfedit.h',
         'fpdfsdk/include/fpdfformfill.h',
-        'fpdfsdk/include/fpdfoom.h',
         'fpdfsdk/include/fpdftext.h',
         'fpdfsdk/include/fpdfview.h',
         'fpdfsdk/include/fpdf_dataavail.h',
@@ -73,7 +71,6 @@
         'fpdfsdk/src/fpdfeditimg.cpp',
         'fpdfsdk/src/fpdfeditpage.cpp',
         'fpdfsdk/src/fpdfformfill.cpp',
-        'fpdfsdk/src/fpdfoom.cpp',
         'fpdfsdk/src/fpdfppo.cpp',
         'fpdfsdk/src/fpdfsave.cpp',
         'fpdfsdk/src/fpdftext.cpp',
@@ -293,7 +290,6 @@
         'core/src/fpdfapi/fpdf_page/fpdf_page_graph_state.cpp',
         'core/src/fpdfapi/fpdf_page/fpdf_page_image.cpp',
         'core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp',
-        'core/src/fpdfapi/fpdf_page/fpdf_page_parser_new.cpp',
         'core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp',
         'core/src/fpdfapi/fpdf_page/fpdf_page_path.cpp',
         'core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp',
@@ -648,7 +644,6 @@
         'core/src/fxge/ge/fx_ge_device.cpp',
         'core/src/fxge/ge/fx_ge_font.cpp',
         'core/src/fxge/ge/fx_ge_fontmap.cpp',
-        'core/src/fxge/ge/fx_ge_linux.cpp',
         'core/src/fxge/ge/fx_ge_path.cpp',
         'core/src/fxge/ge/fx_ge_ps.cpp',
         'core/src/fxge/ge/fx_ge_text.cpp',