Extract shell methods from ApplicationImpl into a base class, and pass this to Initialize() instead.

mojo/services/tracing/public/cpp/tracing_impl.cc

Index: mojo/services/tracing/public/cpp/tracing_impl.cc
diff --git a/mojo/services/tracing/public/cpp/tracing_impl.cc b/mojo/services/tracing/public/cpp/tracing_impl.cc
index b0fd15497e4a59aac91347b850d668ff293ad53d..04cd7d15399b0b23276b0c13f8461c832f3521e8 100644
--- a/mojo/services/tracing/public/cpp/tracing_impl.cc
+++ b/mojo/services/tracing/public/cpp/tracing_impl.cc
@@ -10,7 +10,7 @@
 #include "base/synchronization/lock.h"
 #include "base/threading/platform_thread.h"
 #include "base/trace_event/trace_event_impl.h"
-#include "mojo/shell/public/cpp/application_impl.h"
+#include "mojo/shell/public/cpp/shell.h"
 
 #ifdef NDEBUG
 #include "base/command_line.h"
@@ -41,7 +41,7 @@ TracingImpl::TracingImpl() {
 TracingImpl::~TracingImpl() {
 }
 
-void TracingImpl::Initialize(ApplicationImpl* app) {
+void TracingImpl::Initialize(Shell* shell, const std::string& url) {
   {
     base::AutoLock lock(g_singleton_lock.Get());
     if (g_tracing_singleton_created)
@@ -51,9 +51,9 @@ void TracingImpl::Initialize(ApplicationImpl* app) {
 
   // This will only set the name for the first app in a loaded mojo file. It's
   // up to something like CoreServices to name its own child threads.
-  base::PlatformThread::SetName(app->url());
+  base::PlatformThread::SetName(url);
 
-  connection_ = app->ConnectToApplication("mojo:tracing");
+  connection_ = shell->ConnectToApplication("mojo:tracing");
   connection_->AddService(this);
 
 #ifdef NDEBUG