De-client tracing.TraceController interface

shell/context.h

Index: shell/context.h
diff --git a/shell/context.h b/shell/context.h
index b7f129a21be2fc4d2f54f61b15881d407d58c4d2..a65f02510819e785425b0e8ce5782262a0556c63 100644
--- a/shell/context.h
+++ b/shell/context.h
@@ -9,6 +9,7 @@
 
 #include "base/macros.h"
 #include "mojo/application_manager/application_manager.h"
+#include "mojo/common/trace_controller_impl.h"
 #include "shell/mojo_url_resolver.h"
 #include "shell/task_runners.h"
 
@@ -41,6 +42,7 @@ class Context : ApplicationManager::Delegate {
 
  private:
   class NativeViewportApplicationLoader;
+  class TracingServiceProvider;
 
   // ApplicationManager::Delegate override.
   void OnApplicationError(const GURL& url) override;
@@ -52,6 +54,7 @@ class Context : ApplicationManager::Delegate {
   ApplicationManager application_manager_;
   MojoURLResolver mojo_url_resolver_;
   scoped_ptr<Spy> spy_;
+  scoped_ptr<TracingServiceProvider> tracing_sp_;
 
   DISALLOW_COPY_AND_ASSIGN(Context);
 };