Remove obsolete Mixed Content feature declarations

Remove the unneeded feature declarations now that passive mixed
content is autoupgraded by default.

Bug: 1042877
Change-Id: I60ab635bc7f75527ca27f0657719b1ef42dbe7e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2540654Reviewed-by: Carlos IL <carlosil@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Eric Lawrence [MSFT] <ericlaw@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#828002}

third_party/blink/common/features.cc

@@ -312,9 +312,6 @@ const base::Feature kFontAccessChooser{"FontAccessChooser",
 const base::Feature kPrefetchPrivacyChanges{"PrefetchPrivacyChanges",
                                             base::FEATURE_DISABLED_BY_DEFAULT};
 
-const char kMixedContentAutoupgradeModeParamName[] = "mode";
-const char kMixedContentAutoupgradeModeAllPassive[] = "all-passive";
-
 // Decodes jpeg 4:2:0 formatted images to YUV instead of RGBX and stores in this
 // format in the image decode cache. See crbug.com/919627 for details on the
 // feature.

third_party/blink/public/common/features.h

@@ -87,9 +87,6 @@ BLINK_COMMON_EXPORT extern const base::Feature kFileHandlingAPI;
 BLINK_COMMON_EXPORT extern const base::Feature kAllowSyncXHRInPageDismissal;
 BLINK_COMMON_EXPORT extern const base::Feature kPrefetchPrivacyChanges;
 
-BLINK_COMMON_EXPORT extern const char kMixedContentAutoupgradeModeParamName[];
-BLINK_COMMON_EXPORT extern const char kMixedContentAutoupgradeModeAllPassive[];
-
 BLINK_COMMON_EXPORT extern const base::Feature kDecodeJpeg420ImagesToYUV;
 BLINK_COMMON_EXPORT extern const base::Feature kDecodeLossyWebPImagesToYUV;