Ensure the openGLContext is current before trying to reshape the viewport

webrtc/sdk/objc/Framework/Classes/UI/RTCNSGLVideoView.m

 /*
  *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 59 matching lines @@
   [self teardownDisplayLink];
 }
 
 - (void)drawRect:(NSRect)rect {
   [self drawFrame];
 }
 
 - (void)reshape {
   [super reshape];
   NSRect frame = [self frame];
+  [self ensureGLContext];
   CGLLockContext([[self openGLContext] CGLContextObj]);
   glViewport(0, 0, frame.size.width, frame.size.height);
   CGLUnlockContext([[self openGLContext] CGLContextObj]);
 }
 
 - (void)lockFocus {
   NSOpenGLContext *context = [self openGLContext];
   [super lockFocus];
   if ([context view] != self) {
     [context setView:self];
@@ skipping 94 matching lines @@
   NSOpenGLContext* context = [self openGLContext];
   NSAssert(context, @"context shouldn't be nil");
   if ([NSOpenGLContext currentContext] != context) {
     [context makeCurrentContext];
   }
 }
 
 @end
 
 #endif  // !TARGET_OS_IPHONE