Expose changes in the network quality to the renderers

content/common/renderer.mojom

 // 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 "content/common/native_types.mojom";
 import "ipc/ipc.mojom";
 import "ui/gfx/geometry/mojo/geometry.mojom";
 import "ui/gfx/mojo/icc_profile.mojom";
@@ skipping 139 matching lines @@
   // MSG_ROUTING_NONE.
   CreateFrameProxy(int32 routing_id, int32 render_view_routing_id,
                    int32 opener_routing_id, int32 parent_routing_id,
                    FrameReplicationState replication_state);
 
   // Tells the renderer that the network type has changed so that
   // navigator.onLine and navigator.connection can be updated.
   OnNetworkConnectionChanged(NetworkConnectionType connection_type,
                              double max_bandwidth_mbps);
 
+  // Tells the renderer that the network quality has changed. |http_rtt|,

[nasko, 2017/05/08 18:27:45]

nit: s/renderer/renderer process/

[tbansal1, 2017/05/08 19:50:19]

Done.

+  // |transport_rtt| and |downstream_throughput_kbps| are the computed estimates
+  // of the HTTP RTT, transport RTT and downstream throughput (in kilobits per

[nasko, 2017/05/08 18:27:45]

nit: You can omit the actual names, as the variables are very much
self-describing. Do leave the units of those variables, as that is very
important bit.

[tbansal1, 2017/05/08 19:50:19]

Done.

+  // second), respectively. If an estimate of the HTTP or transport RTT is
+  // unavailable, it will be set to net::nqe::internal::InvalidRTT(). If the

[RyanSturm, 2017/05/08 17:37:20]

nit: Instead of/In addition to net::nqe::internal::InvalidRTT(), you might want
to say -1.

[nasko, 2017/05/08 18:27:45]

I'd rather not use magic values without defining it through a symbolic constant.
There is also base::Optional, though I'm not sure what the overhead would be for
a double parameter.

[tbansal1, 2017/05/08 19:50:19]

is it possible to IPC/mojoify base::Optional?

[tbansal1, 2017/05/08 19:50:19]

I do not think I want to hardcode the number here.

+  // throughput estimate is unavailable, it will be set to
+  // net::nqe::internal::kInvalidThroughput.
+  OnNetworkQualityChanged(double http_rtt_msec, double transport_rtt_msec, double bandwidth_kbps);
+
   // Tells the renderer to suspend/resume the webkit timers. Only for use on
   // Android.
   SetWebKitSharedTimersSuspended(bool suspend);
 
   // Tells the renderer about a scrollbar appearance change. Only for use on
   // OS X.
   UpdateScrollbarTheme(UpdateScrollbarThemeParams params);
 
   // Notification that the OS X Aqua color preferences changed.
   OnSystemColorsChanged(int32 aqua_color_variant, string highlight_text_color,
                         string highlight_color);
 
   // Tells the renderer to empty its plugin list cache, optional reloading
   // pages containing plugins.
   PurgePluginListCache(bool reload_pages);
 };