[ios] Add page load metrics

Measure browser and render generated page
load running time through UMA.

Bug: 996682
Change-Id: Ie6f6445ace8ea77285d819434ec8a0d541f9411b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1760799
Commit-Queue: David Jean <djean@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#699270}

ios/web/navigation/navigation_context_impl.h

@@ -11,6 +11,7 @@
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/timer/elapsed_timer.h"
 #import "ios/web/public/navigation/navigation_context.h"
 #include "url/gurl.h"
 
@@ -61,6 +62,9 @@ class NavigationContextImpl : public NavigationContext {
   void SetResponseHeaders(
       const scoped_refptr<net::HttpResponseHeaders>& response_headers);
 
+  // Get elapsed time since context was created.
+  base::TimeDelta GetElapsedTimeSinceCreation() const;
+
   // Optional unique id of the navigation item associated with this navigaiton.
   int GetNavigationItemUniqueID() const;
   void SetNavigationItemUniqueID(int unique_id);
@@ -133,6 +137,7 @@ class NavigationContextImpl : public NavigationContext {
   bool is_native_content_presented_ = false;
   bool is_placeholder_navigation_ = false;
   NSString* mime_type_ = nil;
+  base::ElapsedTimer elapsed_timer_;
 
   // Holds pending navigation item in this object. Pending item is stored in
   // NavigationContext after context is created. The item is still stored in

ios/web/navigation/navigation_context_impl.mm

@@ -207,6 +207,10 @@ void NavigationContextImpl::SetItem(std::unique_ptr<NavigationItemImpl> item) {
   item_ = std::move(item);
 }
 
+base::TimeDelta NavigationContextImpl::GetElapsedTimeSinceCreation() const {
+  return elapsed_timer_.Elapsed();
+}
+
 NavigationContextImpl::NavigationContextImpl(WebState* web_state,
                                              const GURL& url,
                                              bool has_user_gesture,
@@ -220,7 +224,8 @@ NavigationContextImpl::NavigationContextImpl(WebState* web_state,
       is_same_document_(false),
       error_(nil),
       response_headers_(nullptr),
-      is_renderer_initiated_(is_renderer_initiated) {}
+      is_renderer_initiated_(is_renderer_initiated),
+      elapsed_timer_(base::ElapsedTimer()) {}
 
 NavigationContextImpl::~NavigationContextImpl() = default;
 

ios/web/web_state/ui/crw_web_request_controller.mm

@@ -481,7 +481,18 @@ enum class BackForwardNavigationType {
   } else {
     // There is another pending navigation, so the state is still loading.
   }
+
   self.webState->OnPageLoaded(currentURL, YES);
+
+  if (context) {
+    if (context->IsRendererInitiated()) {
+      UMA_HISTOGRAM_TIMES("PLT.iOS.RendererInitiatedPageLoadTime",
+                          context->GetElapsedTimeSinceCreation());
+    } else {
+      UMA_HISTOGRAM_TIMES("PLT.iOS.BrowserInitiatedPageLoadTime",
+                          context->GetElapsedTimeSinceCreation());
+    }
+  }
 }
 
 // Reports Navigation.IOSWKWebViewSlowFastBackForward UMA. No-op if pending

tools/metrics/histograms/histograms.xml

@@ -106864,6 +106864,28 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="PLT.iOS.BrowserInitiatedPageLoadTime" units="ms"
+    expires_after="2020-08-09">
+  <owner>djean@chromium.org</owner>
+  <owner>eugenebut@chromium.org</owner>
+  <summary>
+    Page load time for Browser-initiated navigations. Recorded when
+    CRWWebRequestController::didFinishWithURL completes successfully. iOS
+    specific.
+  </summary>
+</histogram>
+
+<histogram name="PLT.iOS.RendererInitiatedPageLoadTime" units="ms"
+    expires_after="2020-08-09">
+  <owner>djean@chromium.org</owner>
+  <owner>eugenebut@chromium.org</owner>
+  <summary>
+    Page load time for Renderer-initiated navigations. Recorded when
+    CRWWebRequestController::didFinishWithURL completes successfully. iOS
+    specific.
+  </summary>
+</histogram>
+
 <histogram name="PLT.LoadType" enum="LoadType" expires_after="2016-08-02">
   <obsolete>
     Use PageLoad.PaintTiming.NavigationToFirstContentfulPaint.LoadType.*