Move V8 snapshot loading code from isolate_holder to gin/v8_startup_data.{h,cc}.

ppapi/proxy/pdf_resource.cc

Index: ppapi/proxy/pdf_resource.cc
diff --git a/ppapi/proxy/pdf_resource.cc b/ppapi/proxy/pdf_resource.cc
index e9d3ae893d718db7ffd8e0041c97a6802cf8c298..384fdc90a35bd218251ee1356a79d50e081e87b9 100644
--- a/ppapi/proxy/pdf_resource.cc
+++ b/ppapi/proxy/pdf_resource.cc
@@ -10,7 +10,7 @@
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/utf_string_conversions.h"
-#include "gin/public/isolate_holder.h"
+#include "gin/v8_initializer.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/private/ppb_pdf.h"
 #include "ppapi/proxy/ppapi_messages.h"
@@ -210,8 +210,8 @@ void PDFResource::GetV8ExternalSnapshotData(const char** natives_data_out,
                                             int* natives_size_out,
                                             const char** snapshot_data_out,
                                             int* snapshot_size_out) {
-  gin::IsolateHolder::GetV8ExternalSnapshotData(natives_data_out,
-      natives_size_out, snapshot_data_out, snapshot_size_out);
+  gin::V8Initializer::GetV8ExternalSnapshotData(
+      natives_data_out, natives_size_out, snapshot_data_out, snapshot_size_out);
 }
 
 }  // namespace proxy