Add View::make_inactive() to remove context from rendering thread

View::make_inactive() is called just before termination of the
rendering thread. The implementation must clear the thread's GL
context.

This ensures there is no context still bound to a thread during
GL shutdown. This is needed as GL will not actually delete a
context until it is not active on any thread.

Fixes mapbox/mapbox-gl-native#340

Conflicts:
	common/glfw_view.hpp
	include/llmr/map/view.hpp
	test/headless.cpp

1 files changed, 4 insertions, 0 deletions

diff --git a/include/mbgl/map/view.hpp b/include/mbgl/map/view.hpp
index 92d60d4d02..3e2f1a4b5a 100644
--- a/include/mbgl/map/view.hpp
+++ b/include/mbgl/map/view.hpp
@@ -35,6 +35,10 @@ public:
     // renderer setup since the render thread doesn't switch the contexts.
     virtual void make_active() = 0;
 
+    // Called from the render thread. Makes the GL context inactive in the current
+    // thread. This is called once just before the rendering thread terminates.
+    virtual void make_inactive() = 0;
+
     // Returns the base framebuffer object, if any, and 0 if using the system
     // provided framebuffer.
     virtual unsigned int root_fbo() {