[cleanup] Mark a constructor private to prefer a factory function

MetricsWebContentsObservers should be created through the
|CreateForWebContents| factory function. Hiding the constructor ensures
callers can't accidentally skip initialization handled by the factory
function.

Change-Id: I332aa234c7a307d80d8793ed4ebb4d2efb987448
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2233411Reviewed-by: Steve Kobes <skobes@chromium.org>
Commit-Queue: Tom McKee <tommckee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776039}

components/page_load_metrics/browser/metrics_web_contents_observer.cc

@@ -76,23 +76,6 @@ void MetricsWebContentsObserver::RecordFeatureUsage(
     observer->OnBrowserFeatureUsage(render_frame_host, new_features);
 }
 
-MetricsWebContentsObserver::MetricsWebContentsObserver(
-    content::WebContents* web_contents,
-    std::unique_ptr<PageLoadMetricsEmbedderInterface> embedder_interface)
-    : content::WebContentsObserver(web_contents),
-      in_foreground_(web_contents->GetVisibility() !=
-                     content::Visibility::HIDDEN),
-      embedder_interface_(std::move(embedder_interface)),
-      has_navigated_(false),
-      page_load_metrics_receiver_(web_contents, this) {
-  // Prerenders erroneously report that they are initially visible, so we
-  // manually override visibility state for prerender.
-  if (embedder_interface_->IsPrerender(web_contents))
-    in_foreground_ = false;
-
-  RegisterInputEventObserver(web_contents->GetRenderViewHost());
-}
-
 // static
 MetricsWebContentsObserver* MetricsWebContentsObserver::CreateForWebContents(
     content::WebContents* web_contents,
@@ -188,6 +171,23 @@ void MetricsWebContentsObserver::WillStartNavigationRequest(
   has_navigated_ = true;
 }
 
+MetricsWebContentsObserver::MetricsWebContentsObserver(
+    content::WebContents* web_contents,
+    std::unique_ptr<PageLoadMetricsEmbedderInterface> embedder_interface)
+    : content::WebContentsObserver(web_contents),
+      in_foreground_(web_contents->GetVisibility() !=
+                     content::Visibility::HIDDEN),
+      embedder_interface_(std::move(embedder_interface)),
+      has_navigated_(false),
+      page_load_metrics_receiver_(web_contents, this) {
+  // Prerenders erroneously report that they are initially visible, so we
+  // manually override visibility state for prerender.
+  if (embedder_interface_->IsPrerender(web_contents))
+    in_foreground_ = false;
+
+  RegisterInputEventObserver(web_contents->GetRenderViewHost());
+}
+
 void MetricsWebContentsObserver::WillStartNavigationRequestImpl(
     content::NavigationHandle* navigation_handle) {
   UserInitiatedInfo user_initiated_info(

components/page_load_metrics/browser/metrics_web_contents_observer.h

@@ -87,9 +87,6 @@ class MetricsWebContentsObserver
   static MetricsWebContentsObserver* CreateForWebContents(
       content::WebContents* web_contents,
       std::unique_ptr<PageLoadMetricsEmbedderInterface> embedder_interface);
-  MetricsWebContentsObserver(
-      content::WebContents* web_contents,
-      std::unique_ptr<PageLoadMetricsEmbedderInterface> embedder_interface);
   ~MetricsWebContentsObserver() override;
 
   // Any visibility changes that occur after this method should be ignored since
@@ -175,6 +172,10 @@ class MetricsWebContentsObserver
  private:
   friend class content::WebContentsUserData<MetricsWebContentsObserver>;
 
+  MetricsWebContentsObserver(
+      content::WebContents* web_contents,
+      std::unique_ptr<PageLoadMetricsEmbedderInterface> embedder_interface);
+
   void WillStartNavigationRequestImpl(
       content::NavigationHandle* navigation_handle);