Revert of Use a single CGLContextObj to draw and update the IOSurface

content/browser/compositor/io_surface_layer_mac.mm

Index: content/browser/compositor/io_surface_layer_mac.mm
diff --git a/content/browser/compositor/io_surface_layer_mac.mm b/content/browser/compositor/io_surface_layer_mac.mm
index f88298f6c7cba577f09a48d6bcf83e9c6b9dee19..d09f24c490265f8efda06d5898b603cc261706d1 100644
--- a/content/browser/compositor/io_surface_layer_mac.mm
+++ b/content/browser/compositor/io_surface_layer_mac.mm
@@ -174,7 +174,9 @@
     helper_.reset(new content::IOSurfaceLayerHelper(client, self));
 
     iosurface_ = content::IOSurfaceTexture::Create();
-    if (!iosurface_.get()) {
+    context_ = content::IOSurfaceContext::Get(
+        content::IOSurfaceContext::kCALayerContext);
+    if (!iosurface_.get() || !context_.get()) {
       LOG(ERROR) << "Failed create CompositingIOSurface or context";
       [self resetClient];
       [self release];
@@ -205,11 +207,11 @@
 }
 
 - (void)poisonContextAndSharegroup {
-  iosurface_->context()->PoisonContextAndSharegroup();
+  context_->PoisonContextAndSharegroup();
 }
 
 - (bool)hasBeenPoisoned {
-  return iosurface_->context()->HasBeenPoisoned();
+  return context_->HasBeenPoisoned();
 }
 
 - (float)scaleFactor {
@@ -220,7 +222,7 @@
 
 - (int)rendererID {
   GLint current_renderer_id = -1;
-  if (CGLGetParameter(iosurface_->context()->cgl_context(),
+  if (CGLGetParameter(context_->cgl_context(),
                       kCGLCPCurrentRendererID,
                       &current_renderer_id) == kCGLNoError) {
     return current_renderer_id & kCGLRendererIDMatchingMask;
@@ -255,12 +257,15 @@
 // The remaining methods implement the CAOpenGLLayer interface.
 
 - (CGLPixelFormatObj)copyCGLPixelFormatForDisplayMask:(uint32_t)mask {
-  return CGLRetainPixelFormat(
-      CGLGetPixelFormat(iosurface_->context()->cgl_context()));
+  if (!context_.get())
+    return [super copyCGLPixelFormatForDisplayMask:mask];
+  return CGLRetainPixelFormat(CGLGetPixelFormat(context_->cgl_context()));
 }
 
 - (CGLContextObj)copyCGLContextForPixelFormat:(CGLPixelFormatObj)pixelFormat {
-  return CGLRetainContext(iosurface_->context()->cgl_context());
+  if (!context_.get())
+    return [super copyCGLContextForPixelFormat:pixelFormat];
+  return CGLRetainContext(context_->cgl_context());
 }
 
 - (void)setNeedsDisplay {