The Camera1 and Camera2 API use different size types. Camera1 uses
android.hardware.Camera.Size while Camera2 uses android.util.Size.
android.util.Size is only available from Lollipop forward so this CL
adds a similar Size class in CaptureFormat.
The purpose of this CL is to have a common size type that can be reused
from both Camera1 and Camera2 helper functions such as
CameraEnumerationAndroid.getClosestSupportedSize().
BUG=webrtc:5519
Review-Url: https://codereview.webrtc.org/2066773002
Cr-Commit-Position: refs/heads/master@{#13181}
e6c9e88c18