Add UMA histograms for the inter-process TimeTicks skew.

content/browser/frame_host/render_frame_host_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_frame_host_impl.h"
 
 #include "base/bind.h"
 #include "base/containers/hash_tables.h"
 #include "base/lazy_instance.h"
+#include "base/metrics/histogram.h"
 #include "base/metrics/user_metrics_action.h"
 #include "base/time/time.h"
 #include "content/browser/accessibility/accessibility_mode_helper.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "content/browser/accessibility/browser_accessibility_state_impl.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/cross_site_request_manager.h"
 #include "content/browser/frame_host/cross_process_frame_connector.h"
 #include "content/browser/frame_host/cross_site_transferring_request.h"
 #include "content/browser/frame_host/frame_tree.h"
@@ skipping 721 matching lines @@
     // process. See comments in inter_process_time_ticks_converter.h for more.
     InterProcessTimeTicksConverter converter(
         LocalTimeTicks::FromTimeTicks(send_before_unload_start_time_),
         LocalTimeTicks::FromTimeTicks(base::TimeTicks::Now()),
         RemoteTimeTicks::FromTimeTicks(renderer_before_unload_start_time),
         RemoteTimeTicks::FromTimeTicks(renderer_before_unload_end_time));
     LocalTimeTicks browser_before_unload_end_time =
         converter.ToLocalTimeTicks(
             RemoteTimeTicks::FromTimeTicks(renderer_before_unload_end_time));
     before_unload_end_time = browser_before_unload_end_time.ToTimeTicks();
+
+    // Collect UMA on the inter-process skew.
+    bool is_skew_additive = false;
+    if (converter.IsSkewAdditiveForMetrics()) {
+      is_skew_additive = true;
+      base::TimeDelta skew = converter.GetSkewForMetrics();
+      if (skew >= base::TimeDelta()) {
+        UMA_HISTOGRAM_TIMES(
+            "InterProcessTimeTicks.BrowserBehind_RendererToBrowser", skew);
+      } else {
+        UMA_HISTOGRAM_TIMES(
+            "InterProcessTimeTicks.BrowserAhead_RendererToBrowser", -skew);
+      }
+    }
+    UMA_HISTOGRAM_BOOLEAN(
+        "InterProcessTimeTicks.IsSkewAdditive_RendererToBrowser",
+        is_skew_additive);
   }
   frame_tree_node_->render_manager()->OnBeforeUnloadACK(
       render_view_host_->unload_ack_is_for_cross_site_transition_, proceed,
       before_unload_end_time);
 
   // If canceled, notify the delegate to cancel its pending navigation entry.
   if (!proceed)
     render_view_host_->GetDelegate()->DidCancelLoading();
 }
 
@@ skipping 474 matching lines @@
 }
 
 void RenderFrameHostImpl::CancelSuspendedNavigations() {
   // Clear any state if a pending navigation is canceled or preempted.
   if (suspended_nav_params_)
     suspended_nav_params_.reset();
   navigations_suspended_ = false;
 }
 
 }  // namespace content