Split header modification out of willSendRequest

third_party/WebKit/Source/platform/loader/fetch/FetchContext.h

Index: third_party/WebKit/Source/platform/loader/fetch/FetchContext.h
diff --git a/third_party/WebKit/Source/platform/loader/fetch/FetchContext.h b/third_party/WebKit/Source/platform/loader/fetch/FetchContext.h
index 5097526597e22da6b76283d3cdba239f38d917fa..eceb4034b6b70588b04b03e3b79820b3a997001d 100644
--- a/third_party/WebKit/Source/platform/loader/fetch/FetchContext.h
+++ b/third_party/WebKit/Source/platform/loader/fetch/FetchContext.h
@@ -90,10 +90,13 @@ class PLATFORM_EXPORT FetchContext
   virtual void dispatchDidChangeResourcePriority(unsigned long identifier,
                                                  ResourceLoadPriority,
                                                  int intraPriorityValue);
+
+  virtual void prepareRequest(unsigned long identifier, ResourceRequest&) {}
+
   // The last callback before a request is actually sent to the browser process.
   virtual void dispatchWillSendRequest(
       unsigned long identifier,
-      ResourceRequest&,
+      const ResourceRequest&,
       const ResourceResponse& redirectResponse,
       const FetchInitiatorInfo& = FetchInitiatorInfo());
   virtual void dispatchDidLoadResourceFromMemoryCache(