[page_load_metrics] Rename WebContents{Hidden,Shown} to Page{Hidden,Shown}

Page in back-forward cache can be hidden too, so rename the methods to
avoid confusion.

R=csharrisson@chromium.org
BUG=1001087

Change-Id: I3e2a00ecbaf64275bc5cb46c8ab7662f5ad661cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2004367Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Hajime Hoshi <hajimehoshi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732731}

components/page_load_metrics/browser/metrics_web_contents_observer.cc

@@ -584,15 +584,15 @@ void MetricsWebContentsObserver::OnVisibilityChanged(
 
   if (in_foreground_) {
     if (committed_load_)
-      committed_load_->WebContentsShown();
+      committed_load_->PageShown();
     for (const auto& kv : provisional_loads_) {
-      kv.second->WebContentsShown();
+      kv.second->PageShown();
     }
   } else {
     if (committed_load_)
-      committed_load_->WebContentsHidden();
+      committed_load_->PageHidden();
     for (const auto& kv : provisional_loads_) {
-      kv.second->WebContentsHidden();
+      kv.second->PageHidden();
     }
   }
 }

components/page_load_metrics/browser/page_load_tracker.cc

@@ -298,7 +298,7 @@ void PageLoadTracker::LogAbortChainHistograms(
   }
 }
 
-void PageLoadTracker::WebContentsHidden() {
+void PageLoadTracker::PageHidden() {
   // Only log the first time we background in a given page load.
   if (!first_background_time_.has_value()) {
     // Make sure we either started in the foreground and haven't been
@@ -316,7 +316,7 @@ void PageLoadTracker::WebContentsHidden() {
                              metrics_update_dispatcher_.timing());
 }
 
-void PageLoadTracker::WebContentsShown() {
+void PageLoadTracker::PageShown() {
   // Only log the first time we foreground in a given page load.
   if (!first_foreground_time_.has_value()) {
     // Make sure we either started in the background and haven't been

components/page_load_metrics/browser/page_load_tracker.h

@@ -238,8 +238,8 @@ class PageLoadTracker : public PageLoadMetricsUpdateDispatcher::Client,
       content::NavigationHandle* navigation_handle);
   void FailedProvisionalLoad(content::NavigationHandle* navigation_handle,
                              base::TimeTicks failed_load_time);
-  void WebContentsHidden();
-  void WebContentsShown();
+  void PageHidden();
+  void PageShown();
   void FrameDeleted(content::RenderFrameHost* rfh);
 
   void OnInputEvent(const blink::WebInputEvent& event);