Introduce SavePageAsWebBundle feature flag

We will implement "Save page as Web Bundle" feature behind this flag.

Bug: 1040752
Change-Id: Ia898adf1470730116d96d583aa8acce37bfd8d07
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2007806Reviewed-by: Kunihiko Sakamoto <ksakamoto@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Tsuyoshi Horo <horo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733509}

content/public/common/content_features.cc

@@ -459,6 +459,10 @@ const base::Feature kRunVideoCaptureServiceInBrowserProcess{
     "RunVideoCaptureServiceInBrowserProcess",
     base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Enables saving pages as Web Bundle.
+const base::Feature kSavePageAsWebBundle{"SavePageAsWebBundle",
+                                         base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Make sendBeacon throw for a Blob with a non simple type.
 const base::Feature kSendBeaconThrowForBlobWithNonSimpleType{
     "SendBeaconThrowForBlobWithNonSimpleType",

content/public/common/content_features.h

@@ -102,6 +102,7 @@ CONTENT_EXPORT extern const base::Feature kRequestUnbufferedDispatch;
 CONTENT_EXPORT extern const base::Feature kResamplingInputEvents;
 CONTENT_EXPORT extern const base::Feature
     kRunVideoCaptureServiceInBrowserProcess;
+CONTENT_EXPORT extern const base::Feature kSavePageAsWebBundle;
 CONTENT_EXPORT extern const base::Feature
     kSendBeaconThrowForBlobWithNonSimpleType;
 CONTENT_EXPORT extern const base::Feature kServiceWorkerLongRunningMessage;