Track renderer crash detected on WebState via GlobalWebStateObserver

ios/chrome/browser/metrics/ios_chrome_stability_metrics_provider.mm

 // Copyright 2015 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 "ios/chrome/browser/metrics/ios_chrome_stability_metrics_provider.h"
 
+#import "ios/web/public/web_state/web_state.h"
+
 IOSChromeStabilityMetricsProvider::IOSChromeStabilityMetricsProvider(
     PrefService* local_state)
     : helper_(local_state), recording_enabled_(false) {}
 
 IOSChromeStabilityMetricsProvider::~IOSChromeStabilityMetricsProvider() {}
 
 void IOSChromeStabilityMetricsProvider::OnRecordingEnabled() {
   recording_enabled_ = true;
 }
 
@@ skipping 23 matching lines @@
                            dummy_termination_code);
 }
 
 void IOSChromeStabilityMetricsProvider::WebStateDidStartLoading(
     web::WebState* web_state) {
   if (!recording_enabled_)
     return;
 
   helper_.LogLoadStarted();
 }
+
+void IOSChromeStabilityMetricsProvider::RenderProcessGone(

[Eugene But (OOO till 7-30), 2017/03/27 16:56:26]

I gave some more thoughts about the problem, so sorry for commenting after CL
was landed. Do we even think that GlobalWebStateObserver is a good pattern to
use? GlobalWebStateObserver is not much different from NotificationCenter which
makes code tightly coupled and hard to refactor. Should we reconsider the
ownership model for IOSChromeMetricsServiceClient instead of relying on
"notification center"? 

[pkl (ping after 24h if needed), 2017/04/13 22:29:40]

Let's discuss this in person.

[pkl (ping after 24h if needed), 2017/04/14 21:38:53]

Discussed offline with eugenebut@. This CL should land first so the refactoring
of crash reporting can be completed. This is one step closer to an
implementation that does not involve Tab. Further discussion around using
GlobalWebStateObserver vs. notifications may still be necessary.

+    web::WebState* web_state) {
+  if (!recording_enabled_)
+    return;
+  LogRendererCrash();
+  // TODO(crbug.com/685649): web_state->GetLastCommittedURL() is likely the URL
+  // that caused a renderer crash and can be logged here.
+}