chrome.displaySource custom bindings

extensions/renderer/display_source_custom_bindings.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 "extensions/renderer/display_source_custom_bindings.h"
+
+#include "base/bind.h"
+#include "content/public/child/v8_value_converter.h"
+#include "extensions/renderer/script_context.h"
+#include "third_party/WebKit/public/platform/WebMediaStream.h"
+#include "third_party/WebKit/public/platform/WebMediaStreamTrack.h"
+#include "third_party/WebKit/public/web/WebDOMMediaStreamTrack.h"
+#include "v8/include/v8.h"
+
+namespace extensions {
+
+using content::V8ValueConverter;
+
+namespace {
+const char kErrorNotSupported[] = "Not supported";
+const char kInvalidSinkIdArg[] = "Invalid sink Id argument";
+const char kInvalidAuthInfoArg[] = "Invalid authentication info argument";
+const char kInvalidStreamArgs[] = "Invalid stream arguments";
+const char kSessionAlreadyStarted[] = "The session has been already started";
+const char kSessionAlreadyTerminating[] = "The session is already terminating";
+const char kSessionNotFound[] = "Session not found";
+}  // namespace
+
+DisplaySourceCustomBindings::DisplaySourceCustomBindings(ScriptContext* context)
+    : ObjectBackedNativeHandler(context),
+      weak_factory_(this) {
+  RouteFunction("StartSession",
+                base::Bind(&DisplaySourceCustomBindings::CreateSession,

[asargent_no_longer_on_chrome, 2015/11/26 00:50:07]

nit: any reason for the name mismatch between the js function "StartSession" and
the c++ function "CreateSession"?

[Mikhail, 2015/11/26 13:00:47]

Not really. Renamed.

+                           weak_factory_.GetWeakPtr()));
+  RouteFunction("TerminateSession",
+                base::Bind(&DisplaySourceCustomBindings::TerminateSession,
+                           weak_factory_.GetWeakPtr()));
+}
+
+DisplaySourceCustomBindings::~DisplaySourceCustomBindings() {
+}
+
+void DisplaySourceCustomBindings::Invalidate() {
+  session_map_.clear();
+  terminate_callback_map_.clear();
+  weak_factory_.InvalidateWeakPtrs();
+  ObjectBackedNativeHandler::Invalidate();
+}
+
+namespace {
+
+v8::Local<v8::Value> GetChildValue(v8::Local<v8::Object> value,
+                                   const std::string& key_name,
+                                   v8::Isolate* isolate) {
+  v8::Local<v8::Array> property_names(value->GetOwnPropertyNames());
+  for (uint32 i = 0; i < property_names->Length(); ++i) {
+    v8::Local<v8::Value> key(property_names->Get(i));
+    if (key_name == *v8::String::Utf8Value(key)) {
+      v8::TryCatch try_catch;

[asargent_no_longer_on_chrome, 2015/11/26 00:50:07]

nit: according to the comment at
https://code.google.com/p/chromium/codesearch#chromium/src/v8/include/v8.h&l=...
it looks like they prefer callers switch to the version of the TryCatch
constructor that takes an isolate argument

[Mikhail, 2015/11/26 13:00:47]

Done.

+      v8::Local<v8::Value> child_v8 = value->Get(key);
+      if (try_catch.HasCaught()) {
+        return v8::Null(isolate);
+      }
+      return child_v8;
+    }
+  }
+
+  return v8::Null(isolate);
+}
+
+}  // namespace
+
+void DisplaySourceCustomBindings::CreateSession(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  CHECK_EQ(1, args.Length());
+  CHECK(args[0]->IsObject());
+  v8::Isolate* isolate = context()->isolate();
+  v8::Local<v8::Object> start_info = args[0].As<v8::Object>();
+
+  v8::Local<v8::Value> sink_id_val =
+      GetChildValue(start_info, "sinkId", isolate);
+  if (sink_id_val->IsNull() || sink_id_val->IsUndefined()) {
+    isolate->ThrowException(v8::Exception::Error(
+        v8::String::NewFromUtf8(isolate, kInvalidSinkIdArg)));

[asargent_no_longer_on_chrome, 2015/11/26 00:50:07]

The typical pattern for returning errors from extension functions is to dispatch
the callback with chrome.runtime.lastError set, possibly with a
developer-readable error message in chrome.runtime.lastError.message. Is there a
reason to deviate from that here (and elsewhere below)?

[Mikhail, 2015/11/26 13:00:47]

These are just the arguments sanity checks that can be done right away -- no
need to make them asynchronous, 
other custom bindings throw exceptions the same way (e.g.
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/renderer/ex...
)

[asargent_no_longer_on_chrome, 2015/12/01 01:54:23]

If some errors are reported as exceptions and some via runtime.lastError in the
callback, developers have to write more verbose code. E.g.

function handleError(error) {
  console.error("oops " + error);
}

try {
  chrome.foo.bar(args, function(result) {
    if (chrome.runtime.lastError) {
      handleError(chrome.runtime.lastError.message);
      return;
    }
    ...
  });
} catch (e) {
  handleError(e.message);
}


vs.


chrome.foo.bar(args, function(result) {
  if (chrome.runtime.lastError) {
    console.error("oops " + chrome.runtime.lastError.message);
    return;
  }
  ...
});


Devlin, do you have a preference here?

[Devlin, 2015/12/01 17:48:37]

The standard we should be using is chrome.runtime.lastError.  It has its flaws,
but we should stick with it rather than using multiple error idioms.

+    return;
+  }
+  const int sink_id = sink_id_val->ToInt32(isolate)->Value();
+
+  v8::Local<v8::Value> video_stream_val =
+      GetChildValue(start_info, "videoTrack", isolate);
+  v8::Local<v8::Value> audio_stream_val =
+      GetChildValue(start_info, "audioTrack", isolate);
+
+  if ((video_stream_val->IsNull() || video_stream_val->IsUndefined()) &&
+      (audio_stream_val->IsNull() || audio_stream_val->IsUndefined())) {
+    isolate->ThrowException(v8::Exception::Error(
+        v8::String::NewFromUtf8(isolate, kInvalidStreamArgs)));
+    return;
+  }
+  blink::WebMediaStreamTrack audio_track, video_track;
+
+  if (!video_stream_val->IsNull() && !video_stream_val->IsUndefined()) {
+    CHECK(video_stream_val->IsObject());
+    video_track =
+        blink::WebDOMMediaStreamTrack::fromV8Value(
+            video_stream_val).component();
+    if (video_track.isNull()) {
+      isolate->ThrowException(v8::Exception::Error(
+          v8::String::NewFromUtf8(isolate, kInvalidStreamArgs)));
+      return;
+    }
+  }
+  if (!audio_stream_val->IsNull() && !audio_stream_val->IsUndefined()) {
+    CHECK(audio_stream_val->IsObject());
+    audio_track =
+        blink::WebDOMMediaStreamTrack::fromV8Value(
+            audio_stream_val).component();
+    if (audio_track.isNull()) {
+      isolate->ThrowException(v8::Exception::Error(
+          v8::String::NewFromUtf8(isolate, kInvalidStreamArgs)));
+      return;
+    }
+  }
+
+  v8::Local<v8::Value> auth_info_v8_val =
+      GetChildValue(start_info, "authenticationInfo", isolate);
+  scoped_ptr<V8ValueConverter> converter(V8ValueConverter::create());
+  scoped_ptr<base::Value> auth_info_val(
+      converter->FromV8Value(auth_info_v8_val, context()->v8_context()));
+  scoped_ptr<DisplaySourceAuthInfo> auth_info;
+  if (auth_info_val) {
+    auth_info = DisplaySourceAuthInfo::FromValue(*auth_info_val);
+    if (!auth_info) {
+      isolate->ThrowException(v8::Exception::Error(
+          v8::String::NewFromUtf8(isolate, kInvalidAuthInfoArg)));
+      return;
+    }
+  }
+
+  if (GetDisplaySession(sink_id)) {

[asargent_no_longer_on_chrome, 2015/11/26 00:50:07]

optional: would it make sense to move this check up to line 88 just after we get
the sink_id?

[Mikhail, 2015/11/26 13:00:47]

Makes sense, thus we'll be able to avoid unnecessary checks of the rest of the
arguments 

+    isolate->ThrowException(v8::Exception::Error(v8::String::NewFromUtf8(
+        isolate, kSessionAlreadyStarted)));
+    return;
+  }
+
+  scoped_ptr<DisplaySourceSession> session =
+      DisplaySourceSessionFactory::CreateSession(
+          sink_id, video_track, audio_track, std::move(auth_info));
+  if (!session) {
+    isolate->ThrowException(v8::Exception::Error(v8::String::NewFromUtf8(
+        isolate, kErrorNotSupported)));
+    return;
+  }
+
+  auto on_started_callback = base::Bind(
+      &DisplaySourceCustomBindings::OnSessionStarted,
+      weak_factory_.GetWeakPtr());
+  auto on_terminated_callback = base::Bind(
+      &DisplaySourceCustomBindings::OnSessionTerminated,
+      weak_factory_.GetWeakPtr());
+  auto on_error_callback = base::Bind(
+      &DisplaySourceCustomBindings::OnSessionError,
+      weak_factory_.GetWeakPtr());
+  session->SetCallbacks(on_started_callback,
+                        on_terminated_callback,
+                        on_error_callback);
+  session_map_.insert(std::make_pair(sink_id, std::move(session)));
+  session->Start();
+}
+
+void DisplaySourceCustomBindings::TerminateSession(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  CHECK_EQ(2, args.Length());
+  CHECK(args[0]->IsInt32());
+  CHECK(args[1]->IsNull() || args[1]->IsFunction());
+
+  v8::Isolate* isolate = context()->isolate();
+  v8::Global<v8::Function> terminate_callback;
+  if (!args[1]->IsNull())
+    terminate_callback.Reset(isolate, args[1].As<v8::Function>());
+
+  int sink_id = args[0]->ToInt32(args.GetIsolate())->Value();
+  DisplaySourceSession* session = GetDisplaySession(sink_id);
+  if (!session) {
+    isolate->ThrowException(v8::Exception::Error(v8::String::NewFromUtf8(
+        isolate, kSessionNotFound)));
+    return;
+  }
+
+  if (session->state() == DisplaySourceSession::Terminating) {
+    isolate->ThrowException(v8::Exception::Error(v8::String::NewFromUtf8(
+        isolate, kSessionAlreadyTerminating)));
+    return;
+  }
+
+  if (!terminate_callback.IsEmpty()) {
+    CHECK(terminate_callback_map_.find(sink_id) ==
+          terminate_callback_map_.end());
+    terminate_callback_map_.insert(
+        std::make_pair(sink_id, std::move(terminate_callback)));
+  }
+
+  session->Terminate();
+}
+
+void DisplaySourceCustomBindings::DispatchSessionStarted(int sink_id) const {
+  v8::Isolate* isolate = context()->isolate();
+  v8::HandleScope handle_scope(isolate);
+  v8::Context::Scope context_scope(context()->v8_context());
+  v8::Local<v8::Array> event_args = v8::Array::New(isolate, 1);
+  event_args->Set(0, v8::Integer::New(isolate, sink_id));
+  context()->DispatchEvent("displaySource.onSessionStarted", event_args);
+}
+
+void DisplaySourceCustomBindings::DispatchSessionTerminated(int sink_id) const {
+  v8::Isolate* isolate = context()->isolate();
+  v8::HandleScope handle_scope(isolate);
+  v8::Context::Scope context_scope(context()->v8_context());
+  v8::Local<v8::Array> event_args = v8::Array::New(isolate, 1);
+  event_args->Set(0, v8::Integer::New(isolate, sink_id));
+  context()->DispatchEvent("displaySource.onSessionTerminated", event_args);
+}
+
+void DisplaySourceCustomBindings::DispatchSessionError(
+    int sink_id,
+    DisplaySourceErrorType type,
+    const std::string& message) const {
+  v8::Isolate* isolate = context()->isolate();
+  v8::HandleScope handle_scope(isolate);
+  v8::Context::Scope context_scope(context()->v8_context());
+
+  api::display_source::ErrorInfo error_info;
+  error_info.type = type;
+  if (!message.empty())
+    error_info.description.reset(new std::string(message));
+
+  scoped_ptr<V8ValueConverter> converter(V8ValueConverter::create());
+  v8::Local<v8::Value> info_arg =
+      converter->ToV8Value(error_info.ToValue().get(),
+                           context()->v8_context());
+
+  v8::Local<v8::Array> event_args = v8::Array::New(isolate, 2);
+  event_args->Set(0, v8::Integer::New(isolate, sink_id));
+  event_args->Set(1, info_arg);
+  context()->DispatchEvent("displaySource.onSessionErrorOccured", event_args);
+}
+
+DisplaySourceSession* DisplaySourceCustomBindings::GetDisplaySession(
+    int sink_id) const {
+  auto iter = session_map_.find(sink_id);
+  if (iter != session_map_.end())
+    return iter->second.get();
+  return nullptr;
+}
+
+void DisplaySourceCustomBindings::OnSessionStarted(int sink_id) {
+  DispatchSessionStarted(sink_id);
+}
+
+void DisplaySourceCustomBindings::OnSessionTerminated(int sink_id) {
+  DisplaySourceSession* session = GetDisplaySession(sink_id);
+  CHECK(session);
+  session_map_.erase(sink_id);
+
+  // Call a termination callback if needed.
+  auto iter = terminate_callback_map_.find(sink_id);
+  if (iter != terminate_callback_map_.end()) {
+    v8::Isolate* isolate = context()->isolate();
+    v8::Local<v8::Value> callback_args[1];
+    callback_args[0] = v8::Integer::New(isolate, sink_id);
+    context()->CallFunction(
+        v8::Local<v8::Function>::New(isolate, iter->second), 1,
+        callback_args);
+    terminate_callback_map_.erase(iter);
+  }
+
+  DispatchSessionTerminated(sink_id);
+}
+
+void DisplaySourceCustomBindings::OnSessionError(int sink_id,
+                                                 DisplaySourceErrorType type,
+                                                 const std::string& message) {
+  DisplaySourceSession* session = GetDisplaySession(sink_id);
+  CHECK(session);
+  if (session->state() == DisplaySourceSession::Establishing) {
+    // Error has occured before the session has actually started.
+    session_map_.erase(sink_id);
+  }
+
+  DispatchSessionError(sink_id, type, message);
+}
+
+}  // extensions