Migrate TabControlFeature from 0.5 to 0.6

blimp/client/core/contents/blimp_contents_impl.cc

Index: blimp/client/core/contents/blimp_contents_impl.cc
diff --git a/blimp/client/core/contents/blimp_contents_impl.cc b/blimp/client/core/contents/blimp_contents_impl.cc
index bc4047e3de5111b6e2945861cef87012e3239f81..3e1c4d8eefba49dab0aa3e241768062abbaa820c 100644
--- a/blimp/client/core/contents/blimp_contents_impl.cc
+++ b/blimp/client/core/contents/blimp_contents_impl.cc
@@ -22,10 +22,12 @@ const char kBlimpContentsImplAndroidKey[] = "blimp_contents_impl_android";
 #endif  // OS_ANDROID
 }
 
-BlimpContentsImpl::BlimpContentsImpl()
-    : navigation_controller_(this, nullptr) {}
+BlimpContentsImpl::BlimpContentsImpl(int id)
+    : navigation_controller_(this, nullptr), id_(id) {}
 
-BlimpContentsImpl::~BlimpContentsImpl() {}
+BlimpContentsImpl::~BlimpContentsImpl() {
+  FOR_EACH_OBSERVER(BlimpContentsObserver, observers_, OnContentsDestroyed());
+}
 
 #if defined(OS_ANDROID)