Add check for negative max bitrate in VideoSendStream.
Add check for negative max bitrate in VideoSendStream.

The encoder_max_bitrate_bps_ was checked to be > 0 but since it is
unsigned and the value came from the signed initial_encoder_max_bitrate
negative values were allowed and resulted in using UINT32_MAX.

This CL adds a check for negative input values and uses a safer default.

Bug: None
Change-Id: Ia12ea406091ab9c3a498ecf554f18ba2628ecbe5
Reviewed-on: https://webrtc-review.googlesource.com/61783
Reviewed-by: Erik Språng <3ab8c90c99d6dd7822e0fad803ab0211dd287ae5@webrtc.org>
Commit-Queue: Sebastian Jansson <c24d1bc144eb7c11e553f59153fa17dba85ca83e@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#22453}
TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc