Stop injection when injections are invalidated

extensions/renderer/script_injection.cc

Index: extensions/renderer/script_injection.cc
diff --git a/extensions/renderer/script_injection.cc b/extensions/renderer/script_injection.cc
index da93590c3908c00fb33421a2b3ff9f1077e04b06..cc1a63233ada6dae326790a55dfc45686057c80a 100644
--- a/extensions/renderer/script_injection.cc
+++ b/extensions/renderer/script_injection.cc
@@ -153,7 +153,7 @@ ScriptInjection::InjectionResult ScriptInjection::TryToInject(
 
   if (!injection_host_) {
     NotifyWillNotInject(ScriptInjector::EXTENSION_REMOVED);
-    return INJECTION_FINISHED;  // We're done.
+    return INJECTION_CANCELED;  // We're done.
   }
 
   blink::WebLocalFrame* web_frame = render_frame_->GetWebFrame();
@@ -172,6 +172,8 @@ ScriptInjection::InjectionResult ScriptInjection::TryToInject(
       // notify it upon completion.
       if (result == INJECTION_BLOCKED)
         async_completion_callback_ = async_completion_callback;
+      else if (result == INJECTION_CANCELED)
+        NotifyWillNotInject(ScriptInjector::EXTENSION_REMOVED);
       return result;
   }
 
@@ -218,8 +220,11 @@ ScriptInjection::InjectionResult ScriptInjection::Inject(
   bool should_inject_css = injector_->ShouldInjectCss(run_location_);
   DCHECK(should_inject_js || should_inject_css);
 
-  if (should_inject_js)
+  if (should_inject_js) {
     InjectJs();
+    if (!injection_host_)

[Devlin, 2016/07/08 20:51:09]

A comment explaining why/how this could happen would be useful.

[robwu, 2016/07/09 05:22:02]

Done.

+      return INJECTION_CANCELED;
+  }
   if (should_inject_css)
     InjectCss();
 
@@ -274,7 +279,7 @@ void ScriptInjection::InjectJs() {
         callback.release());
   }
 
-  if (injection_host_->id().type() == HostID::EXTENSIONS)
+  if (injection_host_ && injection_host_->id().type() == HostID::EXTENSIONS)
     UMA_HISTOGRAM_TIMES("Extensions.InjectScriptTime", exec_timer.Elapsed());
 }