Instead of ArrayBuffer, pass blob with printerProvider.onPrintRequested

content/public/browser/browser_context.h

Index: content/public/browser/browser_context.h
diff --git a/content/public/browser/browser_context.h b/content/public/browser/browser_context.h
index 7974c7dc63cdc97c5e28f25d1dffb157558aa737..5a0524ab0810e0031a8881996de33ccdde9b5105 100644
--- a/content/public/browser/browser_context.h
+++ b/content/public/browser/browser_context.h
@@ -17,6 +17,7 @@ class GURL;
 
 namespace base {
 class FilePath;
+class Time;
 }
 
 namespace storage {
@@ -88,6 +89,14 @@ class CONTENT_EXPORT BrowserContext : public base::SupportsUserData {
                                      const char* data, size_t length,
                                      const BlobCallback& callback);
 
+  // |callback| returns a nullptr scoped_ptr on failure.
+  static void CreateFileBackedBlob(BrowserContext* browser_context,
+                                   const base::FilePath& path,
+                                   int64_t offset,
+                                   int64_t size,
+                                   const base::Time& expected_modification_time,
+                                   const BlobCallback& callback);
+
   // Delivers a push message with |data| to the Service Worker identified by
   // |origin| and |service_worker_registration_id|.
   static void DeliverPushMessage(