[Offline Pages] Generate MHTML header in the browser process.

third_party/WebKit/Source/platform/mhtml/MHTMLArchive.h

Index: third_party/WebKit/Source/platform/mhtml/MHTMLArchive.h
diff --git a/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.h b/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.h
index 5c449f2fcbb73cf3bdea89c21f64bd52ab761781..192e8e8ec73afc2de5b4bf93d15da8eec2c79c9f 100644
--- a/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.h
+++ b/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.h
@@ -58,10 +58,10 @@ class PLATFORM_EXPORT MHTMLArchive final
   // Same |boundary| needs to be used for all generateMHTMLHeader and
   // generateMHTMLPart and generateMHTMLFooter calls that belong to the same
   // MHTML document (see also rfc1341, section 7.2.1, "boundary" description).
-  static void GenerateMHTMLHeader(const String& boundary,
-                                  const String& title,
-                                  const String& mime_type,
-                                  Vector<char>& output_buffer);
+  static void GenerateMHTMLHeaderForTesting(const String& boundary,
+                                            const String& title,
+                                            const String& mime_type,
+                                            Vector<char>& output_buffer);
 
   // Serializes SerializedResource as an MHTML part and appends it in
   // |outputBuffer|.