internal/frontend: prefix tab consts with legacy

The existing tab cconsts are prefixed with legacy.

In a follow up CL, we will be using separate tab consts for the unit
page.

Change-Id: I97d0860529afe91f0cfc3be7928636c525941517
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/261723
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
Reviewed-by: Jamal Carvalho <jamal@golang.org>
diff --git a/internal/frontend/directory.go b/internal/frontend/directory.go
index 93f883a..fec14a8 100644
--- a/internal/frontend/directory.go
+++ b/internal/frontend/directory.go
@@ -46,7 +46,7 @@
 	tab := r.FormValue("tab")
 	settings, ok := directoryTabLookup[tab]
 	if tab == "" || !ok || settings.Disabled {
-		tab = tabSubdirectories
+		tab = legacyTabSubdirectories
 		settings = directoryTabLookup[tab]
 	}
 	mi := &internal.ModuleInfo{
diff --git a/internal/frontend/module.go b/internal/frontend/module.go
index 737f291..7ae7c27 100644
--- a/internal/frontend/module.go
+++ b/internal/frontend/module.go
@@ -26,8 +26,8 @@
 	tab := r.FormValue("tab")
 	settings, ok := moduleTabLookup[tab]
 	if !ok {
-		tab = tabOverview
-		settings = moduleTabLookup[tabOverview]
+		tab = legacyTabOverview
+		settings = moduleTabLookup[legacyTabOverview]
 	}
 	canShowDetails := modHeader.IsRedistributable || settings.AlwaysShowDetails
 	var details interface{}
diff --git a/internal/frontend/package.go b/internal/frontend/package.go
index 82e41ad..be94296 100644
--- a/internal/frontend/package.go
+++ b/internal/frontend/package.go
@@ -102,7 +102,7 @@
 			pkgHeader.Module.ModulePath,
 			pkgHeader.Module.LinkVersion),
 	}
-	page.basePage.AllowWideContent = settings.Name == tabDoc
+	page.basePage.AllowWideContent = settings.Name == legacyTabDoc
 	s.servePage(ctx, w, settings.TemplateName, page)
 	return nil
 }
@@ -113,12 +113,12 @@
 // function. If tab is the empty string, the user will be shown the
 // documentation page.
 func packageSettings(tab string) (*TabSettings, error) {
-	if tab == tabDoc {
+	if tab == legacyTabDoc {
 		// Redirect "/<path>?tab=doc" to "/<path>".
 		return nil, derrors.NotFound
 	}
 	if tab == "" {
-		tab = tabDoc
+		tab = legacyTabDoc
 	}
 	settings, ok := packageTabLookup[tab]
 	if !ok {
diff --git a/internal/frontend/tabs.go b/internal/frontend/tabs.go
index 1e6adef..4ba81ee 100644
--- a/internal/frontend/tabs.go
+++ b/internal/frontend/tabs.go
@@ -36,42 +36,42 @@
 var (
 	packageTabSettings = []TabSettings{
 		{
-			Name:         tabDoc,
+			Name:         legacyTabDoc,
 			DisplayName:  "Doc",
 			TemplateName: "pkg_doc.tmpl",
 		},
 		{
-			Name:              tabOverview,
+			Name:              legacyTabOverview,
 			AlwaysShowDetails: true,
 			DisplayName:       "Overview",
 			TemplateName:      "overview.tmpl",
 		},
 		{
-			Name:              tabSubdirectories,
+			Name:              legacyTabSubdirectories,
 			AlwaysShowDetails: true,
 			DisplayName:       "Subdirectories",
 			TemplateName:      "subdirectories.tmpl",
 		},
 		{
-			Name:              tabVersions,
+			Name:              legacyTabVersions,
 			AlwaysShowDetails: true,
 			DisplayName:       "Versions",
 			TemplateName:      "versions.tmpl",
 		},
 		{
-			Name:              tabImports,
+			Name:              legacyTabImports,
 			DisplayName:       "Imports",
 			AlwaysShowDetails: true,
 			TemplateName:      "pkg_imports.tmpl",
 		},
 		{
-			Name:              tabImportedBy,
+			Name:              legacyTabImportedBy,
 			DisplayName:       "Imported By",
 			AlwaysShowDetails: true,
 			TemplateName:      "pkg_importedby.tmpl",
 		},
 		{
-			Name:         tabLicenses,
+			Name:         legacyTabLicenses,
 			DisplayName:  "Licenses",
 			TemplateName: "licenses.tmpl",
 		},
@@ -83,7 +83,7 @@
 
 	moduleTabSettings = []TabSettings{
 		{
-			Name:              tabOverview,
+			Name:              legacyTabOverview,
 			AlwaysShowDetails: true,
 			DisplayName:       "Overview",
 			TemplateName:      "overview.tmpl",
@@ -95,13 +95,13 @@
 			TemplateName:      "subdirectories.tmpl",
 		},
 		{
-			Name:              tabVersions,
+			Name:              legacyTabVersions,
 			AlwaysShowDetails: true,
 			DisplayName:       "Versions",
 			TemplateName:      "versions.tmpl",
 		},
 		{
-			Name:         tabLicenses,
+			Name:         legacyTabLicenses,
 			DisplayName:  "Licenses",
 			TemplateName: "licenses.tmpl",
 		},
@@ -111,9 +111,9 @@
 
 // validDirectoryTabs indicates if a tab is enabled in the directory view.
 var validDirectoryTabs = map[string]bool{
-	tabLicenses:       true,
-	tabOverview:       true,
-	tabSubdirectories: true,
+	legacyTabLicenses:       true,
+	legacyTabOverview:       true,
+	legacyTabSubdirectories: true,
 }
 
 func init() {
@@ -138,14 +138,14 @@
 }
 
 const (
-	tabDetails        = ""
-	tabDoc            = "doc"
-	tabOverview       = "overview"
-	tabSubdirectories = "subdirectories"
-	tabVersions       = "versions"
-	tabImports        = "imports"
-	tabImportedBy     = "importedby"
-	tabLicenses       = "licenses"
+	tabDetails              = ""
+	legacyTabDoc            = "doc"
+	legacyTabOverview       = "overview"
+	legacyTabSubdirectories = "subdirectories"
+	legacyTabVersions       = "versions"
+	legacyTabImports        = "imports"
+	legacyTabImportedBy     = "importedby"
+	legacyTabLicenses       = "licenses"
 )
 
 // fetchDetailsForPackage returns tab details by delegating to the correct detail
@@ -153,19 +153,19 @@
 func fetchDetailsForPackage(r *http.Request, tab string, ds internal.DataSource, um *internal.UnitMeta) (interface{}, error) {
 	ctx := r.Context()
 	switch tab {
-	case tabDoc:
+	case legacyTabDoc:
 		return fetchDocumentationDetails(ctx, ds, um)
-	case tabOverview:
+	case legacyTabOverview:
 		return fetchPackageOverviewDetails(ctx, ds, um, urlIsVersioned(r.URL))
-	case tabSubdirectories:
+	case legacyTabSubdirectories:
 		return fetchDirectoryDetails(ctx, ds, um, false)
-	case tabVersions:
+	case legacyTabVersions:
 		return fetchVersionsDetails(ctx, ds, um.Path, um.ModulePath)
-	case tabImports:
+	case legacyTabImports:
 		return fetchImportsDetails(ctx, ds, um.Path, um.ModulePath, um.Version)
-	case tabImportedBy:
+	case legacyTabImportedBy:
 		return fetchImportedByDetails(ctx, ds, um.Path, um.ModulePath)
-	case tabLicenses:
+	case legacyTabLicenses:
 		return fetchLicensesDetails(ctx, ds, um)
 	}
 	return nil, fmt.Errorf("BUG: unable to fetch details: unknown tab %q", tab)
@@ -176,13 +176,13 @@
 func fetchDetailsForModule(r *http.Request, tab string, ds internal.DataSource, um *internal.UnitMeta) (interface{}, error) {
 	ctx := r.Context()
 	switch tab {
-	case tabOverview:
+	case legacyTabOverview:
 		return fetchOverviewDetails(ctx, ds, um, urlIsVersioned(r.URL))
 	case "packages":
 		return fetchDirectoryDetails(ctx, ds, um, true)
-	case tabVersions:
+	case legacyTabVersions:
 		return fetchModuleVersionsDetails(ctx, ds, um.ModulePath)
-	case tabLicenses:
+	case legacyTabLicenses:
 		return fetchLicensesDetails(ctx, ds, um)
 	}
 	return nil, fmt.Errorf("BUG: unable to fetch details: unknown tab %q", tab)
@@ -193,11 +193,11 @@
 func fetchDetailsForDirectory(r *http.Request, tab string, ds internal.DataSource, um *internal.UnitMeta) (interface{}, error) {
 	ctx := r.Context()
 	switch tab {
-	case tabOverview:
+	case legacyTabOverview:
 		return fetchOverviewDetails(ctx, ds, um, urlIsVersioned(r.URL))
-	case tabSubdirectories:
+	case legacyTabSubdirectories:
 		return fetchDirectoryDetails(ctx, ds, um, false)
-	case tabLicenses:
+	case legacyTabLicenses:
 		return fetchLicensesDetails(ctx, ds, um)
 	}
 	return nil, fmt.Errorf("BUG: unable to fetch details: unknown tab %q", tab)
diff --git a/internal/frontend/unit.go b/internal/frontend/unit.go
index f776108..c94e87d 100644
--- a/internal/frontend/unit.go
+++ b/internal/frontend/unit.go
@@ -83,25 +83,25 @@
 			TemplateName: "unit_details.tmpl",
 		},
 		{
-			Name:              tabVersions,
+			Name:              legacyTabVersions,
 			AlwaysShowDetails: true,
 			DisplayName:       "Versions",
 			TemplateName:      "unit_versions.tmpl",
 		},
 		{
-			Name:              tabImports,
+			Name:              legacyTabImports,
 			AlwaysShowDetails: true,
 			DisplayName:       "Imports",
 			TemplateName:      "unit_imports.tmpl",
 		},
 		{
-			Name:              tabImportedBy,
+			Name:              legacyTabImportedBy,
 			AlwaysShowDetails: true,
 			DisplayName:       "Imported By",
 			TemplateName:      "unit_importedby.tmpl",
 		},
 		{
-			Name:         tabLicenses,
+			Name:         legacyTabLicenses,
 			DisplayName:  "Licenses",
 			TemplateName: "unit_licenses.tmpl",
 		},