[Contextual Search] Add Mojo-enabled API component.

components/contextual_search/renderer/contextual_search_wrapper.cc

+// 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 "components/contextual_search/renderer/contextual_search_wrapper.h"
+
+#include "base/strings/string_util.h"
+#include "content/public/common/service_registry.h"
+#include "content/public/renderer/chrome_object_extensions_utils.h"
+#include "content/public/renderer/render_frame.h"
+#include "gin/arguments.h"
+#include "gin/handle.h"
+#include "gin/object_template_builder.h"
+#include "third_party/WebKit/public/web/WebFrame.h"
+#include "third_party/WebKit/public/web/WebKit.h"
+#include "third_party/WebKit/public/web/WebLocalFrame.h"
+#include "v8/include/v8.h"
+
+namespace {
+
+static const char kContextualSearchObjectName[] = "contextualSearch";
+static const char kSetCaptionMethodName[] = "setCaption";
+
+}  // namespace
+
+namespace contextual_search {
+
+gin::WrapperInfo ContextualSearchWrapper::kWrapperInfo = {
+    gin::kEmbedderNativeGin};
+
+// static
+scoped_ptr<ContextualSearchWrapper> ContextualSearchWrapper::Install(
+    content::RenderFrame* render_frame) {
+  // NOTE: Installing new v8 functions that can access Chrome native code
+  // requires a security review!  We did an exhaustive search for a better
+  // way to implement a communication channel between the page and Chrome,
+  // but found nothing better.
+  // TODO(donnd): use a better communication channel once that becomes
+  // available, e.g. navigator.connect API. See crbug.com/541683.
+  // TODO(donnd): refactor some of this boilerplate into a reusable
+  // method.  This was cribbed from MemoryBenchmarkingExtension.
+  v8::Isolate* isolate = blink::mainThreadIsolate();
+  v8::HandleScope handle_scope(isolate);
+  v8::Local<v8::Context> context =
+      render_frame->GetWebFrame()->mainWorldScriptContext();
+  if (context.IsEmpty())
+    return NULL;
+
+  v8::Context::Scope context_scope(context);
+  scoped_ptr<ContextualSearchWrapper> result(
+      new ContextualSearchWrapper(render_frame));
+  gin::Handle<ContextualSearchWrapper> wrapper =
+      gin::CreateHandle(isolate, result.get());

[jochen (gone - plz use gerrit), 2015/12/02 12:59:15]

CreateHandle() passes ownership of the object to v8 which will delete it
whenever it sees fit (and an undefined point after the render frame died)

[Donn Denman, 2015/12/03 01:21:08]

OK, makes sense.

Changed to store the gin Handle, and clearing it OnDestruct.

+  if (wrapper.IsEmpty())
+    return NULL;
+
+  v8::Local<v8::Object> chrome =
+      content::GetOrCreateChromeObject(isolate, context->Global());
+  chrome->Set(gin::StringToV8(isolate, kContextualSearchObjectName),
+              wrapper.ToV8());
+  return result;
+}
+
+ContextualSearchWrapper::ContextualSearchWrapper(
+    content::RenderFrame* render_frame)
+    : render_frame_(render_frame) {}
+
+ContextualSearchWrapper::~ContextualSearchWrapper() {}
+
+gin::ObjectTemplateBuilder ContextualSearchWrapper::GetObjectTemplateBuilder(
+    v8::Isolate* isolate) {
+  return gin::Wrappable<ContextualSearchWrapper>::GetObjectTemplateBuilder(
+             isolate)
+      .SetMethod(kSetCaptionMethodName, &ContextualSearchWrapper::SetCaption);
+}
+
+void ContextualSearchWrapper::EnsureServiceConnected() {
+  if (!contextual_search_js_api_service_ ||
+      !contextual_search_js_api_service_.is_bound()) {
+    render_frame_->GetServiceRegistry()->ConnectToRemoteService(
+        mojo::GetProxy(&contextual_search_js_api_service_));
+  }
+}
+
+void ContextualSearchWrapper::SetCaption(const std::string& caption,
+                                         bool does_answer) {
+  EnsureServiceConnected();
+  contextual_search_js_api_service_->HandleSetCaption(caption, does_answer);
+}
+
+}  // namespace contextual_search