cros: Fix potential null-deref when sleeping system on views-lock.

chrome/browser/chromeos/power/renderer_freezer.cc

Index: chrome/browser/chromeos/power/renderer_freezer.cc
diff --git a/chrome/browser/chromeos/power/renderer_freezer.cc b/chrome/browser/chromeos/power/renderer_freezer.cc
index 05d4314bf7d3f1e038a831020e49f7e6e507fa8c..9b402eef3462b54de73765e18d8a9703988823b6 100644
--- a/chrome/browser/chromeos/power/renderer_freezer.cc
+++ b/chrome/browser/chromeos/power/renderer_freezer.cc
@@ -148,11 +148,11 @@ void RendererFreezer::OnScreenLockStateChanged(chromeos::ScreenLocker* locker,
   // RendererFreezer::SuspendImminent(), it is guaranteed that the screen locker
   // renderer will not be frozen at any point.
   if (is_locked) {
-    delegate_->SetShouldFreezeRenderer(locker->delegate()
-                                           ->GetWebContents()
-                                           ->GetRenderProcessHost()
-                                           ->GetHandle(),
-                                       false);
+    content::WebContents* web_contents = locker->delegate()->GetWebContents();
+    if (web_contents) {

[Daniel Erat, 2017/05/26 22:10:06]

nit: mind adding a comment here mentioning why this is null? (or TODO pointing
at a bug, if the plan is to switch to the views-based lock screen and this can
be removed later)

[jdufault, 2017/05/26 23:15:20]

Done.

+      delegate_->SetShouldFreezeRenderer(
+          web_contents->GetRenderProcessHost()->GetHandle(), false);
+    }
   }
 }