Add a chrome://webapks page.

chrome/common/url_constants.cc

Index: chrome/common/url_constants.cc
diff --git a/chrome/common/url_constants.cc b/chrome/common/url_constants.cc
index e0aa7118c4f779302166368fb518f802551fd522..592f5b166db08f24a8408f10f4064d90857b6fad 100644
--- a/chrome/common/url_constants.cc
+++ b/chrome/common/url_constants.cc
@@ -112,6 +112,7 @@ const char kChromeUINativeHistoryURL[] = "chrome-native://history/";
 const char kChromeUINativePhysicalWebDiagnosticsURL[] =
     "chrome-native://physical-web-diagnostics/";
 const char kChromeUINativeRecentTabsURL[] = "chrome-native://recent-tabs/";
+const char kChromeUIWebApksURL[] = "chrome://webapks/";
 #endif
 
 #if defined(OS_CHROMEOS)
@@ -287,6 +288,7 @@ const char kChromeUIOfflineInternalsHost[] = "offline-internals";
 const char kChromeUIPhysicalWebDiagnosticsHost[] = "physical-web-diagnostics";
 const char kChromeUIPopularSitesInternalsHost[] = "popular-sites-internals";
 const char kChromeUISnippetsInternalsHost[] = "snippets-internals";
+const char kChromeUIWebApksHost[] = "webapks";
 #endif
 
 #if defined(ENABLE_VR_SHELL) || defined(ENABLE_WEBVR)
@@ -690,6 +692,7 @@ const char* const kChromeHostURLs[] = {
     kChromeUIOfflineInternalsHost,
     kChromeUIPopularSitesInternalsHost,
     kChromeUISnippetsInternalsHost,
+    kChromeUIWebApksHost,
 #endif
 #if defined(OS_CHROMEOS)
     kChromeUICertificateManagerHost,