Allow textures to be moved from one GL context group to another.

gpu/command_buffer/service/context_group.h

Index: gpu/command_buffer/service/context_group.h
===================================================================
--- gpu/command_buffer/service/context_group.h	(revision 133928)
+++ gpu/command_buffer/service/context_group.h	(working copy)
@@ -22,9 +22,10 @@
 
 namespace gles2 {
 
+class BufferManager;
 class GLES2Decoder;
-class BufferManager;
 class FramebufferManager;
+class MailboxManager;
 class RenderbufferManager;
 class ProgramManager;
 class ShaderManager;
@@ -37,7 +38,8 @@
  public:
   typedef scoped_refptr<ContextGroup> Ref;
 
-  explicit ContextGroup(bool bind_generates_resource);
+  explicit ContextGroup(MailboxManager* mailbox_manager,
+                        bool bind_generates_resource);
   ~ContextGroup();
 
   // This should only be called by GLES2Decoder. This must be paired with a
@@ -49,6 +51,10 @@
   // It should only be called by GLES2Decoder.
   void Destroy(bool have_context);
 
+  MailboxManager* mailbox_manager() const {
+    return mailbox_manager_.get();
+  }
+
   bool bind_generates_resource() {
     return bind_generates_resource_;
   }
@@ -117,6 +123,8 @@
   bool QueryGLFeature(GLenum pname, GLint min_required, GLint* v);
   bool QueryGLFeatureU(GLenum pname, GLint min_required, uint32* v);
 
+  scoped_refptr<MailboxManager> mailbox_manager_;
+
   // Whether or not this context is initialized.
   int num_contexts_;
   bool enforce_gl_minimums_;