Remove usage of HostZoomMap from c/b/loader via ReadyToCommitNavigation

content/common/host_zoom.mojom

Index: content/common/host_zoom.mojom
diff --git a/content/common/host_zoom.mojom b/content/common/host_zoom.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..844ba07d0f21ee751656bd5ed0a731251afc089c
--- /dev/null
+++ b/content/common/host_zoom.mojom
@@ -0,0 +1,12 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module content.mojom;
+
+import "url/mojo/url.mojom";
+
+interface HostZoom {
+  // Sets the host zoom level for the given url, called just before commit.
+  SetHostZoomLevel(url.mojom.Url url, double zoom_level);
+};