Introduce COEP feature flag

This CL only introduces a new flag. The feature flag is in the network
service because COEP expands CORP which is implemented there.

Bug: 887967
Change-Id: I146c9b99e61de8f68f13f5fe2f93437418328a1c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1702366
Commit-Queue: Yutaka Hirano <[email protected]>
Reviewed-by: Kinuko Yasuda <[email protected]>
Auto-Submit: Yutaka Hirano <[email protected]>
Cr-Commit-Position: refs/heads/master@{#678138}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 379a33c..acf6e01 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -451,6 +451,9 @@
 extern const char kEnableOutOfBlinkCorsName[];
 extern const char kEnableOutOfBlinkCorsDescription[];
 
+extern const char kCrossOriginEmbedderPolicyName[];
+extern const char kCrossOriginEmbedderPolicyDescription[];
+
 extern const char kVizDisplayCompositorName[];
 extern const char kVizDisplayCompositorDescription[];