Eliminate kMojoChannelToken usage for render processes

content/child/child_thread_impl.cc

Index: content/child/child_thread_impl.cc
diff --git a/content/child/child_thread_impl.cc b/content/child/child_thread_impl.cc
index f0b739ca5daecae7b3ce2c3d4c2d7b2ae77233a2..562ebf828a038e95808741db210cfcaa128df135 100644
--- a/content/child/child_thread_impl.cc
+++ b/content/child/child_thread_impl.cc
@@ -54,6 +54,7 @@
 #include "content/common/child_process_messages.h"
 #include "content/common/in_process_child_thread_params.h"
 #include "content/common/mojo/constants.h"
+#include "content/public/common/connection_filter.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/mojo_channel_switches.h"
 #include "content/public/common/mojo_shell_connection.h"
@@ -70,6 +71,7 @@
 #include "mojo/edk/embedder/platform_channel_pair.h"
 #include "mojo/edk/embedder/scoped_ipc_support.h"
 #include "services/shell/public/cpp/connector.h"
+#include "services/shell/public/cpp/interface_factory.h"
 #include "services/shell/public/cpp/interface_provider.h"
 #include "services/shell/public/cpp/interface_registry.h"
 #include "services/shell/runner/common/client_util.h"
@@ -257,6 +259,37 @@ void InitializeMojoIPCChannel() {
   mojo::edk::SetParentPipeHandle(std::move(platform_channel));
 }
 
+class ChannelBootstrapFilter
+    : public ConnectionFilter,
+      public shell::InterfaceFactory<IPC::mojom::ChannelBootstrap> {
+ public:
+  explicit ChannelBootstrapFilter(IPC::mojom::ChannelBootstrapPtrInfo bootstrap)
+      : bootstrap_(std::move(bootstrap)) {}
+
+ private:
+  // ConnectionFilter:
+  bool OnConnect(const shell::Identity& remote_identity,
+                 shell::InterfaceRegistry* registry,
+                 shell::Connector* connector) override {
+    if (remote_identity.name() != kBrowserMojoApplicationName)
+      return false;
+
+    registry->AddInterface<IPC::mojom::ChannelBootstrap>(this);
+    return true;
+  }
+
+  // shell::InterfaceFactory<IPC::mojom::ChannelBootstrap>:
+  void Create(const shell::Identity& remote_identity,
+              IPC::mojom::ChannelBootstrapRequest request) override {
+    DCHECK(bootstrap_.is_valid());
+    mojo::FuseInterface(std::move(request), std::move(bootstrap_));
+  }
+
+  IPC::mojom::ChannelBootstrapPtrInfo bootstrap_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChannelBootstrapFilter);
+};
+
 }  // namespace
 
 ChildThread* ChildThread::Get() {
@@ -377,15 +410,29 @@ void ChildThreadImpl::ConnectChannel(bool use_mojo_channel,
   bool create_pipe_now = true;
   if (use_mojo_channel) {
     VLOG(1) << "Mojo is enabled on child";
+    std::string channel_token;
     mojo::ScopedMessagePipeHandle handle;
     if (!IsInBrowserProcess()) {
-      DCHECK(!handle.is_valid());
-      handle = mojo::edk::CreateChildMessagePipe(
+      channel_token =
           base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
-              switches::kMojoChannelToken));
+              switches::kMojoChannelToken);
+    } else {
+      channel_token = ipc_token;
+    }
+
+    if (!channel_token.empty()) {
+      // TODO(rockot): Remove all paths which lead to this branch. The Channel
+      // connection should always be established by a shell connection from the
+      // browser. http://crbug.com/623396.
+      handle = mojo::edk::CreateChildMessagePipe(channel_token);
     } else {
-      handle = mojo::edk::CreateChildMessagePipe(ipc_token);
+      DCHECK(mojo_shell_connection_);
+      IPC::mojom::ChannelBootstrapPtr bootstrap;
+      handle = mojo::GetProxy(&bootstrap).PassMessagePipe();
+      mojo_shell_connection_->AddConnectionFilter(
+          base::MakeUnique<ChannelBootstrapFilter>(bootstrap.PassInterface()));
     }
+
     DCHECK(handle.is_valid());
     channel_->Init(
         IPC::ChannelMojo::CreateClientFactory(
@@ -459,9 +506,6 @@ void ChildThreadImpl::Init(const Options& options) {
     // ConnectionFilter.
     mojo_shell_connection_->SetupInterfaceRequestProxies(
         GetInterfaceRegistry(), remote_interfaces);
-
-    if (options.auto_start_mojo_shell_connection)
-      StartMojoShellConnection();
   }
 
   sync_message_filter_ = channel_->CreateSyncMessageFilter();
@@ -532,8 +576,14 @@ void ChildThreadImpl::Init(const Options& options) {
   IPC::AttachmentBroker* broker = IPC::AttachmentBroker::GetGlobal();
   if (broker && !broker->IsPrivilegedBroker())
     broker->RegisterBrokerCommunicationChannel(channel_.get());
+
   ConnectChannel(options.use_mojo_channel, options.in_process_ipc_token);
 
+  // This must always be done after ConnectChannel, because ConnectChannel() may
+  // add a ConnectionFilter to the connection.
+  if (options.auto_start_mojo_shell_connection && mojo_shell_connection_)
+    StartMojoShellConnection();
+
   int connection_timeout = kConnectionTimeoutS;
   std::string connection_override =
       base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(