Expose loading state from Blimp to Tab

blimp/client/core/contents/android/blimp_contents_observer_proxy.cc

Index: blimp/client/core/contents/android/blimp_contents_observer_proxy.cc
diff --git a/blimp/client/core/contents/android/blimp_contents_observer_proxy.cc b/blimp/client/core/contents/android/blimp_contents_observer_proxy.cc
index 1e57b3c5fcc87fd79d1eb0d2c51c0aee2fe77adf..5584ce82d6d79d245013909bc19cd0d3818cf33a 100644
--- a/blimp/client/core/contents/android/blimp_contents_observer_proxy.cc
+++ b/blimp/client/core/contents/android/blimp_contents_observer_proxy.cc
@@ -52,5 +52,11 @@ void BlimpContentsObserverProxy::OnNavigationStateChanged() {
   Java_BlimpContentsObserverProxy_onNavigationStateChanged(env, java_obj_);
 }
 
+void BlimpContentsObserverProxy::OnLoadingStateChanged(bool loading) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  Java_BlimpContentsObserverProxy_onLoadingStateChanged(env, java_obj_,
+                                                        loading);
+}
+
 }  // namespace client
 }  // namespace blimp