[Presentation API / Media Router] Clean up default pres URL logic.

chrome/browser/media/android/router/media_router_dialog_controller_android.cc

Index: chrome/browser/media/android/router/media_router_dialog_controller_android.cc
diff --git a/chrome/browser/media/android/router/media_router_dialog_controller_android.cc b/chrome/browser/media/android/router/media_router_dialog_controller_android.cc
index e0e05336efbf653efbb9702f6b065fa5cf047844..fe4d5aa01ddd3a228f77b65c5b4b0a0d95b795bd 100644
--- a/chrome/browser/media/android/router/media_router_dialog_controller_android.cc
+++ b/chrome/browser/media/android/router/media_router_dialog_controller_android.cc
@@ -10,6 +10,8 @@
 #include "chrome/browser/media/router/media_router.h"
 #include "chrome/browser/media/router/media_router_factory.h"
 #include "chrome/browser/media/router/media_source.h"
+#include "chrome/browser/media/router/media_source_helper.h"
+#include "chrome/browser/media/router/presentation_request.h"
 #include "chrome/browser/sessions/session_tab_helper.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
@@ -36,16 +38,17 @@ MediaRouterDialogControllerAndroid::GetOrCreateForWebContents(
 
 void MediaRouterDialogControllerAndroid::OnSinkSelected(
     JNIEnv* env, jobject obj, jstring jsink_id) {
-  scoped_ptr<CreatePresentationSessionRequest>
-      request(TakePresentationRequest());
+  scoped_ptr<CreatePresentationSessionRequest> create_session_request(
+      TakePresentationRequest());

[mlamouri (slow - plz ping), 2015/10/27 18:42:51]

I think the name |create_session_request| is very confusing. Could you rename
this |presentation_request_creator| or something similar so it doesn't look like
a function.

Also, please initialize with = instead of () if possible:
  scoped_ptr<T> foo = TakeFoo();

[imcheng, 2015/10/27 20:50:14]

Why is it confusing? It is an object that represents input and callback for a
request to create a presentation session. |presentation_request_creator| doesn't
sound right to me; it doesn't create presentation requests. See other comments
as well.

Changed to move operator.

 
-  const std::string& source_id = request->media_source().id();
-  const GURL& origin = request->frame_url().GetOrigin();
+  const MediaSource::Id source_id(
+      create_session_request->presentation_request().GetMediaSource()).id());
+  const GURL origin(presentation_request.frame_url().GetOrigin());
 
   std::vector<MediaRouteResponseCallback> route_response_callbacks;
   route_response_callbacks.push_back(
       base::Bind(&CreatePresentationSessionRequest::HandleRouteResponse,
-                 base::Passed(&request)));
+                 base::Passed(&create_session_request)));
 
   MediaRouter* router = MediaRouterFactory::GetApiForBrowserContext(
       initiator()->GetBrowserContext());
@@ -108,7 +111,7 @@ void MediaRouterDialogControllerAndroid::CreateMediaRouterDialog() {
   JNIEnv* env = base::android::AttachCurrentThread();
 
   const MediaSource::Id& media_source_id =
-      presentation_request()->media_source().id();
+      create_session_request()->presentation_request()->GetMediaSource().id();
   ScopedJavaLocalRef<jstring> jsource_urn =
       base::android::ConvertUTF8ToJavaString(env, media_source_id);