Synchronize calls to EGL10/EGL14.eglCreateContext on EglBase.lock. The
reason is that a deadlock between the remote render thread in
eglSwapBuffers and MediaCodecVideoEncoder eglCreateContext was observed.
The function calls that are now synchronized on EglBase.lock are:
eglCreateContext, eglMakeCurrent, eglSwapBuffers, and
SurfaceTexture.updateTexImage.
BUG=webrtc:5702
Review-Url: https://codereview.webrtc.org/1937933002
Cr-Commit-Position: refs/heads/master@{#12603}
ddf165393f