[Extensions Bindings] Add ExtensionBindingsSystem interface; hook it up

extensions/renderer/js_extension_bindings_system.cc

+// Copyright 2016 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 "extensions/renderer/js_extension_bindings_system.h"
+
+#include "base/command_line.h"
+#include "base/strings/string_split.h"
+#include "content/public/child/v8_value_converter.h"
+#include "content/public/common/content_switches.h"
+#include "extensions/common/extension.h"
+#include "extensions/common/extension_urls.h"
+#include "extensions/common/extensions_client.h"
+#include "extensions/common/features/feature.h"
+#include "extensions/common/features/feature_provider.h"
+#include "extensions/common/manifest_constants.h"
+#include "extensions/common/manifest_handlers/externally_connectable.h"
+#include "extensions/renderer/binding_generating_native_handler.h"
+#include "extensions/renderer/renderer_extension_registry.h"
+#include "extensions/renderer/resource_bundle_source_map.h"
+#include "extensions/renderer/script_context.h"
+#include "gin/converter.h"
+#include "v8/include/v8.h"
+
+namespace extensions {
+
+namespace {
+
+static const char kEventDispatchFunction[] = "dispatchEvent";
+
+// Gets |field| from |object| or creates it as an empty object if it doesn't
+// exist.
+v8::Local<v8::Object> GetOrCreateObject(const v8::Local<v8::Object>& object,
+                                        const std::string& field,
+                                        v8::Isolate* isolate) {
+  v8::Local<v8::String> key = v8::String::NewFromUtf8(isolate, field.c_str());
+  // If the object has a callback property, it is assumed it is an unavailable
+  // API, so it is safe to delete. This is checked before GetOrCreateObject is
+  // called.
+  if (object->HasRealNamedCallbackProperty(key)) {
+    object->Delete(key);
+  } else if (object->HasRealNamedProperty(key)) {
+    v8::Local<v8::Value> value = object->Get(key);
+    CHECK(value->IsObject());
+    return v8::Local<v8::Object>::Cast(value);
+  }
+
+  v8::Local<v8::Object> new_object = v8::Object::New(isolate);
+  object->Set(key, new_object);
+  return new_object;
+}
+
+// Returns the global value for "chrome" from |context|. If one doesn't exist
+// creates a new object for it. If a chrome property exists on the window
+// already (as in the case when a script did `window.chrome = true`), returns
+// an empty object.
+v8::Local<v8::Object> GetOrCreateChrome(ScriptContext* context) {
+  v8::Local<v8::String> chrome_string(
+      v8::String::NewFromUtf8(context->isolate(), "chrome"));
+  v8::Local<v8::Object> global(context->v8_context()->Global());
+  v8::Local<v8::Value> chrome(global->Get(chrome_string));
+  if (chrome->IsUndefined()) {
+    chrome = v8::Object::New(context->isolate());
+    global->Set(chrome_string, chrome);
+  }
+  return chrome->IsObject() ? chrome.As<v8::Object>() : v8::Local<v8::Object>();
+}
+
+v8::Local<v8::Object> GetOrCreateBindObjectIfAvailable(
+    const std::string& api_name,
+    std::string* bind_name,
+    ScriptContext* context) {
+  std::vector<std::string> split = base::SplitString(
+      api_name, ".", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
+
+  v8::Local<v8::Object> bind_object;
+
+  // Check if this API has an ancestor. If the API's ancestor is available and
+  // the API is not available, don't install the bindings for this API. If
+  // the API is available and its ancestor is not, delete the ancestor and
+  // install the bindings for the API. This is to prevent loading the ancestor
+  // API schema if it will not be needed.
+  //
+  // For example:
+  //  If app is available and app.window is not, just install app.
+  //  If app.window is available and app is not, delete app and install
+  //  app.window on a new object so app does not have to be loaded.
+  const FeatureProvider* api_feature_provider =
+      FeatureProvider::GetAPIFeatures();
+  std::string ancestor_name;
+  bool only_ancestor_available = false;
+
+  for (size_t i = 0; i < split.size() - 1; ++i) {
+    ancestor_name += (i ? "." : "") + split[i];
+    if (api_feature_provider->GetFeature(ancestor_name) &&
+        context->GetAvailability(ancestor_name).is_available() &&
+        !context->GetAvailability(api_name).is_available()) {
+      only_ancestor_available = true;
+      break;
+    }
+
+    if (bind_object.IsEmpty()) {
+      bind_object = GetOrCreateChrome(context);
+      if (bind_object.IsEmpty())
+        return v8::Local<v8::Object>();
+    }
+    bind_object = GetOrCreateObject(bind_object, split[i], context->isolate());
+  }
+
+  if (only_ancestor_available)
+    return v8::Local<v8::Object>();
+
+  DCHECK(bind_name);
+  *bind_name = split.back();
+
+  return bind_object.IsEmpty() ? GetOrCreateChrome(context) : bind_object;
+}
+
+// Determines if a ScriptContext can connect to any externally_connectable-
+// enabled extension.
+bool IsRuntimeAvailableToContext(ScriptContext* context) {
+  for (const auto& extension :
+       *RendererExtensionRegistry::Get()->GetMainThreadExtensionSet()) {
+    ExternallyConnectableInfo* info = static_cast<ExternallyConnectableInfo*>(
+        extension->GetManifestData(manifest_keys::kExternallyConnectable));
+    if (info && info->matches.MatchesURL(context->url()))
+      return true;
+  }
+  return false;
+}
+
+// Creates the event bindings if necessary for the given |context|.
+void MaybeCreateEventBindings(ScriptContext* context) {
+  // chrome.Event is part of the public API (although undocumented). Make it
+  // lazily evalulate to Event from event_bindings.js. For extensions only
+  // though, not all webpages!
+  if (!context->extension())
+    return;
+  v8::Local<v8::Object> chrome = GetOrCreateChrome(context);
+  if (chrome.IsEmpty())
+    return;
+  context->module_system()->SetLazyField(chrome, "Event", kEventBindings,
+                                         "Event");
+}
+
+}  // namespace
+
+JsExtensionBindingsSystem::JsExtensionBindingsSystem(
+    ResourceBundleSourceMap* source_map,
+    std::unique_ptr<RequestSender> request_sender)
+    : source_map_(source_map), request_sender_(std::move(request_sender)) {}
+
+JsExtensionBindingsSystem::~JsExtensionBindingsSystem() {}
+
+void JsExtensionBindingsSystem::DidCreateScriptContext(ScriptContext* context) {
+  MaybeCreateEventBindings(context);
+}
+
+void JsExtensionBindingsSystem::WillReleaseScriptContext(
+    ScriptContext* context) {
+  // TODO(kalman): Make |request_sender| use |context->AddInvalidationObserver|.
+  // In fact |request_sender_| should really be owned by ScriptContext.
+  request_sender_->InvalidateSource(context);
+}
+
+void JsExtensionBindingsSystem::UpdateBindingsForContext(
+    ScriptContext* context) {
+  v8::HandleScope handle_scope(context->isolate());
+  v8::Context::Scope context_scope(context->v8_context());
+
+  // TODO(kalman): Make the bindings registration have zero overhead then run
+  // the same code regardless of context type.
+  switch (context->context_type()) {
+    case Feature::UNSPECIFIED_CONTEXT:
+    case Feature::WEB_PAGE_CONTEXT:
+    case Feature::BLESSED_WEB_PAGE_CONTEXT:
+      // Hard-code registration of any APIs that are exposed to webpage-like
+      // contexts, because it's too expensive to run the full bindings code.
+      // All of the same permission checks will still apply.
+      if (context->GetAvailability("app").is_available())
+        RegisterBinding("app", context);
+      if (context->GetAvailability("webstore").is_available())
+        RegisterBinding("webstore", context);
+      if (context->GetAvailability("dashboardPrivate").is_available())
+        RegisterBinding("dashboardPrivate", context);
+      if (IsRuntimeAvailableToContext(context))
+        RegisterBinding("runtime", context);
+      break;
+
+    case Feature::SERVICE_WORKER_CONTEXT:
+      DCHECK(ExtensionsClient::Get()
+                 ->ExtensionAPIEnabledInExtensionServiceWorkers());
+    // Intentional fallthrough.
+    case Feature::BLESSED_EXTENSION_CONTEXT:
+    case Feature::UNBLESSED_EXTENSION_CONTEXT:
+    case Feature::CONTENT_SCRIPT_CONTEXT:
+    case Feature::WEBUI_CONTEXT: {
+      // Extension context; iterate through all the APIs and bind the available
+      // ones.
+      const FeatureProvider* api_feature_provider =
+          FeatureProvider::GetAPIFeatures();
+      for (const auto& map_entry : api_feature_provider->GetAllFeatures()) {
+        // Internal APIs are included via require(api_name) from internal code
+        // rather than chrome[api_name].
+        if (map_entry.second->IsInternal())
+          continue;
+
+        // If this API has a parent feature (and isn't marked 'noparent'),
+        // then this must be a function or event, so we should not register.
+        if (api_feature_provider->GetParent(map_entry.second.get()) != nullptr)
+          continue;
+
+        // Skip chrome.test if this isn't a test.
+        if (map_entry.first == "test" &&
+            !base::CommandLine::ForCurrentProcess()->HasSwitch(
+                ::switches::kTestType)) {
+          continue;
+        }
+
+        if (context->IsAnyFeatureAvailableToContext(*map_entry.second)) {
+          // TODO(lazyboy): RegisterBinding() uses |source_map_|, any thread
+          // safety issue?
+          RegisterBinding(map_entry.first, context);
+        }
+      }
+      break;
+    }
+  }
+}
+
+void JsExtensionBindingsSystem::HandleResponse(int request_id,
+                                               bool success,
+                                               const base::ListValue& response,
+                                               const std::string& error) {
+  request_sender_->HandleResponse(request_id, success, response, error);
+}
+
+RequestSender* JsExtensionBindingsSystem::GetRequestSender() {
+  return request_sender_.get();
+}
+
+void JsExtensionBindingsSystem::DispatchEventInContext(
+    const std::string& event_name,
+    const base::ListValue* event_args,
+    const base::DictionaryValue* filtering_info,
+    ScriptContext* context) {
+  v8::HandleScope handle_scope(context->isolate());
+  v8::Context::Scope context_scope(context->v8_context());
+
+  std::vector<v8::Local<v8::Value>> arguments;
+  arguments.push_back(gin::StringToSymbol(context->isolate(), event_name));
+
+  {
+    std::unique_ptr<content::V8ValueConverter> converter(
+        content::V8ValueConverter::create());
+    arguments.push_back(
+        converter->ToV8Value(event_args, context->v8_context()));
+    if (!filtering_info->empty()) {
+      arguments.push_back(
+          converter->ToV8Value(filtering_info, context->v8_context()));
+    }
+  }
+
+  context->module_system()->CallModuleMethodSafe(
+      kEventBindings, kEventDispatchFunction, arguments.size(),
+      arguments.data());
+}
+
+void JsExtensionBindingsSystem::RegisterBinding(const std::string& api_name,
+                                                ScriptContext* context) {
+  std::string bind_name;
+  v8::Local<v8::Object> bind_object =
+      GetOrCreateBindObjectIfAvailable(api_name, &bind_name, context);
+
+  // Empty if the bind object failed to be created, probably because the
+  // extension overrode chrome with a non-object, e.g. window.chrome = true.
+  if (bind_object.IsEmpty())
+    return;
+
+  v8::Local<v8::String> v8_bind_name =
+      v8::String::NewFromUtf8(context->isolate(), bind_name.c_str());
+  if (bind_object->HasRealNamedProperty(v8_bind_name)) {
+    // The bind object may already have the property if the API has been
+    // registered before (or if the extension has put something there already,
+    // but, whatevs).
+    //
+    // In the former case, we need to re-register the bindings for the APIs
+    // which the extension now has permissions for (if any), but not touch any
+    // others so that we don't destroy state such as event listeners.
+    //
+    // TODO(kalman): Only register available APIs to make this all moot.
+    if (bind_object->HasRealNamedCallbackProperty(v8_bind_name))
+      return;  // lazy binding still there, nothing to do
+    if (bind_object->Get(v8_bind_name)->IsObject())
+      return;  // binding has already been fully installed
+  }
+
+  ModuleSystem* module_system = context->module_system();
+  if (!source_map_->Contains(api_name)) {
+    module_system->RegisterNativeHandler(
+        api_name,
+        std::unique_ptr<NativeHandler>(
+            new BindingGeneratingNativeHandler(context, api_name, "binding")));
+    module_system->SetNativeLazyField(bind_object, bind_name, api_name,
+                                      "binding");
+  } else {
+    module_system->SetLazyField(bind_object, bind_name, api_name, "binding");
+  }
+}
+
+}  // namespace extensions