Remove the BackspaceGoesBack flag.

chrome/common/chrome_features.cc

Index: chrome/common/chrome_features.cc
diff --git a/chrome/common/chrome_features.cc b/chrome/common/chrome_features.cc
index 4181b412a392b441feb1f30bd86c2fc5fb199234..7e8134d0f4d2b559f2c9b7a24b5a85bcc681491e 100644
--- a/chrome/common/chrome_features.cc
+++ b/chrome/common/chrome_features.cc
@@ -60,12 +60,6 @@ const base::Feature kBackgroundModeAllowRestart{
     "BackgroundModeAllowRestart", base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // defined(OS_WIN) || defined(OS_LINUX)
 
-// Enables the Backspace key to navigate back in the browser, as well as
-// Shift+Backspace to navigate forward.
-const base::Feature kBackspaceGoesBackFeature {
-  "BackspaceGoesBack", base::FEATURE_DISABLED_BY_DEFAULT
-};
-
 // Enables or disables whether permission prompts are automatically blocked
 // after the user has explicitly dismissed them too many times.
 const base::Feature kBlockPromptsIfDismissedOften{