Add SetVideoMode API to avsettings

chromecast/public/avsettings.h

Index: chromecast/public/avsettings.h
diff --git a/chromecast/public/avsettings.h b/chromecast/public/avsettings.h
index be12e2183c309a8e4e343073c9374a511652cd5f..17e68cda223da0801a4841d45c4998a1870219d5 100644
--- a/chromecast/public/avsettings.h
+++ b/chromecast/public/avsettings.h
@@ -291,6 +291,27 @@ class AvSettings {
 
   // Gets the current HDR output type.
   virtual HdrOutputType GetHdrOutputType() = 0;
+
+  // Sets the video mode according to the given parameters:

[gfhuang, 2016/10/03 20:33:59]

HDMI video mode

[almasrymina1, 2016/10/03 20:51:54]

Done.

+  //
+  // allow_4k: if false, the resolution set will not be a 4K resolution.
+  //
+  // optimize_for_fps: *Attempts* to pick a refresh rate optimal for the given
+  // content frame rate. The content frame rate is expressed as framerate
+  // * 100. I.e. 24hz -> 2400, 23.98hz -> 23.98, etc.  Values <= 0 are ignored.
+  //
+  // Returns false if it will not attempt to set the video mode. This could be
+  // due to:
+  // HDMI state is not connected.
+  // Resolution set is already the best resolution with the params provided.
+  //
+  // Returns true otherwise.
+  //
+  // When this API return true, A SCREEN_INFO_CHANGED event fires when the video
+  // mode setting completes. When this API returns false, no event is fired.

[halliwell, 2016/10/03 20:27:34]

Could we just tighten up/organise this whole comment a bit?
* Use |allow_4k| notation for arguments
* 23.98hz example is wrong, should say 2398
* Return value description is very disorganised, could be more succinct and keep
the whole description of true/false together.  e.g. something like this:

Returns:
- true if mode change is beginning.  Caller should wait for SCREEN_INFO_CHANGED
event for mode change to complete.
- false if no made change has begun.  This could be because HDMI is
disconnected, or the current resolution is already good for the given
parameters.

[almasrymina1, 2016/10/03 20:51:54]

Done. I couldn't think of a better name, so I just made it very clear in the
comment. Suggestions welcome though :)

+  //
+  // This API only applies to devices that output HDMI.

[gfhuang, 2016/10/03 20:33:59]

", otherwise, simply return false"  (or true?)

[almasrymina1, 2016/10/03 20:51:54]

Done.

+  virtual bool SetHdmiVideoMode(bool allow_4k, int optimize_for_fps) = 0;
 };
 
 }  // namespace chromecast