NoStatePrefetch: Remove PrerenderContents::SetPrerenderMode()

PrerenderContents::SetPrerenderMode() is called with
mojom::PrerenderMode::kPrefetchOnly right after an instance of
PrerenderContents is constructed. For code simplification, that should
be set in the constructor instead of the public setter function.

Historically, the setter function was meaningful because that can be
called with another value of mojom::PrerenderMode ("kPrerender") but
that was removed due to deprecation of the legacy prerender.

Bug: 755921
Change-Id: I01d9987765411ef79d8596c71a14d3d9674dcbd9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2589574Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837039}

components/no_state_prefetch/browser/prerender_contents.cc

@@ -129,8 +129,7 @@ PrerenderContents::PrerenderContents(
     const content::Referrer& referrer,
     const base::Optional<url::Origin>& initiator_origin,
     Origin origin)
-    : prerender_mode_(prerender::mojom::PrerenderMode::kNoPrerender),
-      prerendering_has_started_(false),
+    : prerendering_has_started_(false),
       prerender_manager_(prerender_manager),
       delegate_(std::move(delegate)),
       prerender_url_(url),
@@ -170,11 +169,6 @@ bool PrerenderContents::Init() {
   return AddAliasURL(prerender_url_);
 }
 
-void PrerenderContents::SetPrerenderMode(prerender::mojom::PrerenderMode mode) {
-  DCHECK(!prerendering_has_started_);
-  prerender_mode_ = mode;
-}
-
 // static
 PrerenderContents::Factory* PrerenderContents::CreateFactory() {
   return new PrerenderContentsFactoryImpl();

components/no_state_prefetch/browser/prerender_contents.h

@@ -111,9 +111,6 @@ class PrerenderContents : public content::NotificationObserver,
 
   bool Init();
 
-  // Set the mode of this contents. This must be called before prerender has
-  // started.
-  void SetPrerenderMode(prerender::mojom::PrerenderMode mode);
   prerender::mojom::PrerenderMode prerender_mode() const {
     return prerender_mode_;
   }
@@ -241,7 +238,8 @@ class PrerenderContents : public content::NotificationObserver,
   std::unique_ptr<content::WebContents> CreateWebContents(
       content::SessionStorageNamespace* session_storage_namespace);
 
-  prerender::mojom::PrerenderMode prerender_mode_;
+  const prerender::mojom::PrerenderMode prerender_mode_ =
+      mojom::PrerenderMode::kPrefetchOnly;
   bool prerendering_has_started_;
 
   // Time at which we started to load the URL.  This is used to compute

components/no_state_prefetch/browser/prerender_manager.cc

@@ -324,10 +324,8 @@ PrerenderManager::GetAllNoStatePrefetchingContentsForTesting() const {
 
   for (const auto& prerender : active_prerenders_) {
     WebContents* contents = prerender->contents()->prerender_contents();
-    if (contents && prerender->contents()->prerender_mode() ==
-                        prerender::mojom::PrerenderMode::kPrefetchOnly) {
+    if (contents)
       result.push_back(contents);
-    }
   }
 
   return result;
@@ -609,8 +607,6 @@ PrerenderManager::AddPrerenderWithPreconnectFallback(
       CreatePrerenderContents(url, referrer, initiator_origin, origin);
   DCHECK(prerender_contents);
   PrerenderContents* prerender_contents_ptr = prerender_contents.get();
-  prerender_contents_ptr->SetPrerenderMode(
-      prerender::mojom::PrerenderMode::kPrefetchOnly);
   active_prerenders_.push_back(
       std::make_unique<PrerenderData>(this, std::move(prerender_contents),
                                       GetExpiryTimeForNewPrerender(origin)));