Mark methods with override in pdf/

pdf/pdfium/pdfium_engine.cc

Index: pdf/pdfium/pdfium_engine.cc
diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index 9bf10fb7c515dbe0390117372f5955b2f79ff83e..90c4df56f62cb167e24df8c0b2f2780acb317cf6 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -11,6 +11,7 @@
 #include "base/i18n/icu_encoding_detection.h"
 #include "base/i18n/icu_string_conversions.h"
 #include "base/json/json_writer.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
@@ -3777,12 +3778,11 @@ ScopedUnsupportedFeature::~ScopedUnsupportedFeature() {
   g_engine_for_unsupported = old_engine_;
 }
 
-PDFEngineExports* PDFEngineExports::Create() {
-  return new PDFiumEngineExports;
-}
-
 namespace {
 
+base::LazyInstance<PDFiumEngineExports>::Leaky g_pdf_engine_exports =
+    LAZY_INSTANCE_INITIALIZER;
+
 int CalculatePosition(FPDF_PAGE page,
                       const PDFiumEngineExports::RenderingSettings& settings,
                       pp::Rect* dest) {
@@ -3848,6 +3848,10 @@ int CalculatePosition(FPDF_PAGE page,
 
 }  // namespace
 
+PDFEngineExports* PDFEngineExports::Get() {
+  return g_pdf_engine_exports.Pointer();
+}
+
 #if defined(OS_WIN)
 bool PDFiumEngineExports::RenderPDFPageToDC(const void* pdf_buffer,
                                             int buffer_size,
@@ -3931,7 +3935,7 @@ bool PDFiumEngineExports::RenderPDFPageToDC(const void* pdf_buffer,
   FPDF_CloseDocument(doc);
   return true;
 }
-#endif  // OS_WIN
+#endif  // defined(OS_WIN)
 
 bool PDFiumEngineExports::RenderPDFPageToBitmap(
     const void* pdf_buffer,