[inspector] added check that context always survives inspected context

src/inspector/inspected-context.cc

 // Copyright 2016 the V8 project 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 "src/inspector/inspected-context.h"
 
 #include "src/inspector/injected-script.h"
 #include "src/inspector/string-util.h"
 #include "src/inspector/v8-console.h"
 #include "src/inspector/v8-inspector-impl.h"
 #include "src/inspector/v8-value-copier.h"
 
 #include "include/v8-inspector.h"
 
 namespace v8_inspector {
 
-void InspectedContext::weakCallback(
-    const v8::WeakCallbackInfo<InspectedContext>& data) {
-  InspectedContext* context = data.GetParameter();
-  if (!context->m_context.IsEmpty()) {
-    context->m_context.Reset();
-    data.SetSecondPassCallback(&InspectedContext::weakCallback);
-  } else {
-    context->m_inspector->discardInspectedContext(context->m_contextGroupId,
-                                                  context->m_contextId);
-  }
+namespace {
+
+void clearContext(const v8::WeakCallbackInfo<v8::Global<v8::Context>>& data) {
+  // Inspected context is created in V8InspectorImpl::contextCreated method
+  // and destroyed in V8InspectorImpl::contextDestroyed.
+  // Both methods takes valid v8::Local<v8::Context> handle to the same context,
+  // it means that context is created before InspectedContext constructor and is
+  // always destroyed after InspectedContext destructor therefore this callback
+  // should be never called.
+  // It's possible only if inspector client doesn't call contextDestroyed which
+  // is considered an error.
+  CHECK(false);
+  data.GetParameter()->Reset();
 }
 
-void InspectedContext::consoleWeakCallback(
-    const v8::WeakCallbackInfo<InspectedContext>& data) {
-  data.GetParameter()->m_console.Reset();
-}
+}  // namespace
 
 InspectedContext::InspectedContext(V8InspectorImpl* inspector,
                                    const V8ContextInfo& info, int contextId)
     : m_inspector(inspector),
       m_context(info.context->GetIsolate(), info.context),
       m_contextId(contextId),
       m_contextGroupId(info.contextGroupId),
       m_origin(toString16(info.origin)),
       m_humanReadableName(toString16(info.humanReadableName)),
       m_auxData(toString16(info.auxData)),
       m_reported(false) {
-  m_context.SetWeak(this, &InspectedContext::weakCallback,
+  m_context.SetWeak(&m_context, &clearContext,
                     v8::WeakCallbackType::kParameter);
 
   v8::Isolate* isolate = m_inspector->isolate();
   v8::Local<v8::Object> global = info.context->Global();
   v8::Local<v8::Object> console =
       V8Console::createConsole(this, info.hasMemoryOnConsole);
   if (!global
            ->Set(info.context, toV8StringInternalized(isolate, "console"),
                  console)
            .FromMaybe(false))
     return;
   m_console.Reset(isolate, console);
-  m_console.SetWeak(this, &InspectedContext::consoleWeakCallback,
-                    v8::WeakCallbackType::kParameter);
+  m_console.SetWeak();
 }
 
 InspectedContext::~InspectedContext() {
-  if (!m_context.IsEmpty() && !m_console.IsEmpty()) {
+  if (!m_console.IsEmpty()) {
     v8::HandleScope scope(isolate());
     V8Console::clearInspectedContextIfNeeded(context(),
                                              m_console.Get(isolate()));
   }
 }
 
 v8::Local<v8::Context> InspectedContext::context() const {
   return m_context.Get(isolate());
 }
 
 v8::Isolate* InspectedContext::isolate() const {
   return m_inspector->isolate();
 }
 
 void InspectedContext::createInjectedScript() {
   DCHECK(!m_injectedScript);
   m_injectedScript = InjectedScript::create(this);
 }
 
 void InspectedContext::discardInjectedScript() { m_injectedScript.reset(); }
 
 }  // namespace v8_inspector