gpu: Refactor to support cross-channel shared textures

gpu/command_buffer/service/context_group.cc

Index: gpu/command_buffer/service/context_group.cc
diff --git a/gpu/command_buffer/service/context_group.cc b/gpu/command_buffer/service/context_group.cc
index d1821d7be7234b771b6754c7259a06725125cdb0..725fba25070f9e570a4e63e96b805963f9094418 100644
--- a/gpu/command_buffer/service/context_group.cc
+++ b/gpu/command_buffer/service/context_group.cc
@@ -170,6 +170,7 @@ bool ContextGroup::Initialize(
                                             feature_info_.get(),
                                             max_texture_size,
                                             max_cube_map_texture_size));
+  texture_manager_->set_framebuffer_manager(framebuffer_manager_.get());
 
   const GLint kMinTextureImageUnits = 8;
   const GLint kMinVertexTextureImageUnits = 0;
@@ -251,6 +252,8 @@ void ContextGroup::Destroy(GLES2Decoder* decoder, bool have_context) {
 
   if (framebuffer_manager_ != NULL) {
     framebuffer_manager_->Destroy(have_context);
+    if (texture_manager_)
+      texture_manager_->set_framebuffer_manager(NULL);
     framebuffer_manager_.reset();
   }