Move content's shell connections to the IO thread

content/public/common/mojo_shell_connection.h

Index: content/public/common/mojo_shell_connection.h
diff --git a/content/public/common/mojo_shell_connection.h b/content/public/common/mojo_shell_connection.h
index 7014034b26ebf23ddbb4bc388fe4d6ad9479e371..577f1282b0cefa8ca55fa71ca2c79b699b6fbf11 100644
--- a/content/public/common/mojo_shell_connection.h
+++ b/content/public/common/mojo_shell_connection.h
@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "base/callback_forward.h"
+#include "base/sequenced_task_runner.h"
 #include "content/common/content_export.h"
 #include "content/public/common/mojo_application_info.h"
 #include "services/shell/public/cpp/identity.h"
@@ -16,11 +17,14 @@
 namespace shell {
 class Connection;
 class Connector;
-class ServiceContext;
+class InterfaceProvider;
+class InterfaceRegistry;
 }
 
 namespace content {
 
+class ConnectionFilter;
+
 // Encapsulates a connection to a //services/shell.
 // Access a global instance on the thread the ServiceContext was bound by
 // calling Holder::Get().
@@ -55,13 +59,21 @@ class CONTENT_EXPORT MojoShellConnection {
   // called before the MojoShellConnection has been created.
   static void SetFactoryForTest(Factory* factory);
 
-  // Creates a MojoShellConnection from |request|.
+  // Creates a MojoShellConnection from |request|. The connection binds
+  // its interfaces and accept new connections on |io_task_runner| only. Note
+  // that no incoming connections are accepted until Start() is called.
   static std::unique_ptr<MojoShellConnection> Create(
-      shell::mojom::ServiceRequest request);
+      shell::mojom::ServiceRequest request,
+      scoped_refptr<base::SequencedTaskRunner> io_task_runner);
+
+  // Begins accepting incoming connections. Connection filters MUST be added
+  // before calling this in order to avoid races. See AddConnectionFilter()
+  // below.
+  virtual void Start() = 0;
 
-  // Returns the bound shell::ServiceContext object.
-  // TODO(rockot): remove.
-  virtual shell::ServiceContext* GetShellConnection() = 0;
+  // Sets a closure to be invoked once the connection receives an Initialize()
+  // request from the shell.
+  virtual void SetInitializeHandler(const base::Closure& handler) = 0;
 
   // Returns the shell::Connector received via this connection's Service
   // implementation. Use this to initiate connections as this object's Identity.
@@ -76,12 +88,31 @@ class CONTENT_EXPORT MojoShellConnection {
   // run immediately before returning from this function.
   virtual void SetConnectionLostClosure(const base::Closure& closure) = 0;
 
-  // Allows the caller to expose interfaces to the caller using the identity of
-  // this object's Service. As distinct from MergeService() and
-  // AddServiceRequestHandler() which specify unique identities for the
-  // registered services.
-  virtual void MergeService(std::unique_ptr<shell::Service> service) = 0;
-  virtual void MergeService(shell::Service* service) = 0;
+  // Provides an InterfaceRegistry to forward incoming interface requests to
+  // on the MojoShellConnection's own thread if they aren't bound by the
+  // connection's internal InterfaceRegistry on the IO thread.
+  //
+  // Also configures |interface_provider| to forward all of its outgoing
+  // interface requests to the connection's internal remote interface provider.
+  //
+  // Note that neither |interface_registry| or |interface_provider| is owned
+  // and both MUST outlive the MojoShellConnection.
+  //
+  // TODO(rockot): Remove this. It's a temporary solution to avoid porting all
+  // relevant code to ConnectionFilters at once.
+  virtual void SetupInterfaceRequestProxies(
+      shell::InterfaceRegistry* registry,
+      shell::InterfaceProvider* provider) = 0;
+
+  // Allows the caller to filter inbound connections and/or expose interfaces
+  // on them. |filter| may be created on any thread, but will be used and
+  // destroyed exclusively on the IO thread (the thread corresponding to
+  // |io_task_runner| passed to Create() above.)
+  //
+  // Connection filters MUST be added before calling Start() in order to avoid
+  // races.
+  virtual void AddConnectionFilter(
+      std::unique_ptr<ConnectionFilter> filter) = 0;
 
   // Adds an embedded service to this connection's ServiceFactory.
   // |info| provides details on how to construct new instances of the