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

content/test/test_blink_web_unit_test_support.cc

Index: content/test/test_blink_web_unit_test_support.cc
diff --git a/content/test/test_blink_web_unit_test_support.cc b/content/test/test_blink_web_unit_test_support.cc
index 81a0552b2ebddb2e8981356b68e17e0b99f289b0..49b5113e3a8c3a413d6a51e2ba2abcafcb437483 100644
--- a/content/test/test_blink_web_unit_test_support.cc
+++ b/content/test/test_blink_web_unit_test_support.cc
@@ -41,7 +41,7 @@
 #endif
 
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
-#include "gin/public/isolate_holder.h"
+#include "gin/v8_initializer.h"
 #endif
 
 namespace content {
@@ -55,7 +55,7 @@ TestBlinkWebUnitTestSupport::TestBlinkWebUnitTestSupport() {
   mock_clipboard_.reset(new MockWebClipboardImpl());
 
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
-  gin::IsolateHolder::LoadV8Snapshot();
+  gin::V8Initializer::LoadV8Snapshot();
 #endif
 
   if (base::MessageLoopProxy::current()) {