Create a about handler component.

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index d1447cb90a006ad77b6c59f5057447d69f5492e9..02830ba1ea684f6e71989f4f3031c7a858ff6305 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -90,6 +90,7 @@ source_set("browser") {
     "//chrome/browser/ui",
     "//chrome/common",
     "//chrome/common/net",
+    "//components/about_handler",
     "//components/autofill/core/browser",
     "//components/bookmarks/browser",
     "//components/bookmarks/managed",
@@ -253,6 +254,7 @@ source_set("browser") {
       "//chrome/browser/devtools",
       "//chrome/browser/resources:component_extension_resources",
       "//chrome/installer/util",
+      "//components/about_handler",
       "//components/app_modal",
       "//components/autofill/content/browser",
       "//components/browsing_data",
@@ -1055,6 +1057,7 @@ source_set("test_support") {
     "//chrome/browser",
     "//chrome/common",
     "//chrome/common/safe_browsing:proto",
+    "//components/about_handler",
     "//components/invalidation/impl",
     "//components/invalidation/impl:test_support",
     "//components/password_manager/core/browser:test_support",