Add function for getting supported H264 level from max resolution and fps

webrtc/common_video/h264/profile_level_id.h

Index: webrtc/common_video/h264/profile_level_id.h
diff --git a/webrtc/common_video/h264/profile_level_id.h b/webrtc/common_video/h264/profile_level_id.h
index 44292631cb51212c55d86d598d738d9c276c9c8e..59f297a8669dd327ba9d1e7d637026a1cb054ca5 100644
--- a/webrtc/common_video/h264/profile_level_id.h
+++ b/webrtc/common_video/h264/profile_level_id.h
@@ -60,6 +60,12 @@ struct ProfileLevelId {
 // profile level id.
 rtc::Optional<ProfileLevelId> ParseProfileLevelId(const char* str);
 
+// Given that a decoder supports up to a given frame size (in pixels) at up to a
+// given number of frames per second, return the highest H.264 level where it
+// can guarantee that it will be able to support all valid encoded streams that
+// are within that level.
+rtc::Optional<Level> SupportedLevel(int max_frame_pixel_count, int max_fps);

[hta-webrtc, 2016/11/08 09:21:16]

Suggest using a float or double for max_fps. The conversion between the two
forms is hurtful in the codebase, and whenever we get content at 29.94 FPS, odd
stuff happens.

[magjed_webrtc, 2016/11/08 10:29:23]

Done, changed to float.

+
 // Returns canonical string representation as three hex bytes of the profile
 // level id, or returns nothing for invalid profile level ids.
 rtc::Optional<std::string> ProfileLevelIdToString(