Implement CachedMetadata handling on MojoAsyncResourceHandler

content/browser/loader/mojo_async_resource_handler.h

Index: content/browser/loader/mojo_async_resource_handler.h
diff --git a/content/browser/loader/mojo_async_resource_handler.h b/content/browser/loader/mojo_async_resource_handler.h
index 894ff848c0c1faf04c7c4f1aa750f6de87ec31a2..ebb38b2f3da220cf986b8ff2e49a4fd40deb8c2c 100644
--- a/content/browser/loader/mojo_async_resource_handler.h
+++ b/content/browser/loader/mojo_async_resource_handler.h
@@ -23,6 +23,7 @@
 #include "url/gurl.h"
 
 namespace net {
+class IOBufferWithSize;
 class URLRequest;
 }
 
@@ -74,6 +75,7 @@ class CONTENT_EXPORT MojoAsyncResourceHandler
   // These functions can be overriden only for tests.
   virtual MojoResult BeginWrite(void** data, uint32_t* available);
   virtual MojoResult EndWrite(uint32_t written);
+  virtual net::IOBufferWithSize* GetResponseMetadata(net::URLRequest* request);
 
  private:
   class SharedWriter;