Add Feature Flag for On-The-Fly MHTML Hashing

Added new feature flag which all future work for On-The-Fly MHTML
hashing will be hidden behind.

Bug: 915966
Change-Id: I63e4453aef70d9cfb07066c2073ff640609328f0
Reviewed-on: https://chromium-review.googlesource.com/c/1372414
Reviewed-by: Elly Fong-Jones <[email protected]>
Reviewed-by: Carlos Knippschild <[email protected]>
Reviewed-by: Dan H <[email protected]>
Commit-Queue: Mark Lieu <[email protected]>
Cr-Commit-Position: refs/heads/master@{#620837}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 1c03096..b05b9cf 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -848,6 +848,9 @@
 extern const char kOmniboxVoiceSearchAlwaysVisibleName[];
 extern const char kOmniboxVoiceSearchAlwaysVisibleDescription[];
 
+extern const char kOnTheFlyMhtmlHashComputationName[];
+extern const char kOnTheFlyMhtmlHashComputationDescription[];
+
 extern const char kOopRasterizationName[];
 extern const char kOopRasterizationDescription[];