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refactor: use platform-specific TaskRunner to print (#27225)

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Shelley Vohr 2021-01-13 09:17:11 -08:00 committed by GitHub
parent 1c66cacf70
commit 0599487e65
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2 changed files with 34 additions and 5 deletions
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38
shell/browser/api/electron_api_web_contents.cc
View file

@ -422,8 +422,11 @@ bool IsDeviceNameValid(const base::string16& device_name) {
}
base::string16 GetDefaultPrinterAsync() {
base::ScopedBlockingCall scoped_blocking_call(FROM_HERE,
base::BlockingType::MAY_BLOCK);
#if defined(OS_WIN)
// Blocking is needed here because Windows printer drivers are oftentimes
// not thread-safe and have to be accessed on the UI thread.
base::ThreadRestrictions::ScopedAllowIO allow_io;
#endif
scoped_refptr<printing::PrintBackend> print_backend =
printing::PrintBackend::CreateInstance(
@ -441,6 +444,29 @@ base::string16 GetDefaultPrinterAsync() {
}
return base::UTF8ToUTF16(printer_name);
}
// Copied from
// chrome/browser/ui/webui/print_preview/local_printer_handler_default.cc:L36-L54
scoped_refptr<base::TaskRunner> CreatePrinterHandlerTaskRunner() {
// USER_VISIBLE because the result is displayed in the print preview dialog.
#if !defined(OS_WIN)
static constexpr base::TaskTraits kTraits = {
base::MayBlock(), base::TaskPriority::USER_VISIBLE};
#endif
#if defined(USE_CUPS)
// CUPS is thread safe.
return base::ThreadPool::CreateTaskRunner(kTraits);
#elif defined(OS_WIN)
// Windows drivers are likely not thread-safe and need to be accessed on the
// UI thread.
return content::GetUIThreadTaskRunner(
{base::MayBlock(), base::TaskPriority::USER_VISIBLE});
#else
// Be conservative on unsupported platforms.
return base::ThreadPool::CreateSingleThreadTaskRunner(kTraits);
#endif
}
#endif
struct UserDataLink : public base::SupportsUserData::Data {
@ -591,6 +617,7 @@ WebContents::WebContents(v8::Isolate* isolate,
devtools_file_system_indexer_(new DevToolsFileSystemIndexer),
file_task_runner_(
base::ThreadPool::CreateSequencedTaskRunner({base::MayBlock()})),
print_task_runner_(CreatePrinterHandlerTaskRunner()),
weak_factory_(this) {
#if BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
// WebContents created by extension host will have valid ViewType set.
@ -624,6 +651,7 @@ WebContents::WebContents(v8::Isolate* isolate,
devtools_file_system_indexer_(new DevToolsFileSystemIndexer),
file_task_runner_(
base::ThreadPool::CreateSequencedTaskRunner({base::MayBlock()})),
print_task_runner_(CreatePrinterHandlerTaskRunner()),
weak_factory_(this) {
DCHECK(type != Type::kRemote)
<< "Can't take ownership of a remote WebContents";
@ -639,6 +667,7 @@ WebContents::WebContents(v8::Isolate* isolate,
devtools_file_system_indexer_(new DevToolsFileSystemIndexer),
file_task_runner_(
base::ThreadPool::CreateSequencedTaskRunner({base::MayBlock()})),
print_task_runner_(CreatePrinterHandlerTaskRunner()),
weak_factory_(this) {
// Read options.
options.Get("backgroundThrottling", &background_throttling_);
@ -2521,9 +2550,8 @@ void WebContents::Print(gin::Arguments* args) {
settings.SetIntKey(printing::kSettingDpiVertical, dpi);
}
base::ThreadPool::PostTaskAndReplyWithResult(
FROM_HERE, {base::MayBlock(), base::TaskPriority::USER_BLOCKING},
base::BindOnce(&GetDefaultPrinterAsync),
print_task_runner_->PostTaskAndReplyWithResult(
FROM_HERE, base::BindOnce(&GetDefaultPrinterAsync),
base::BindOnce(&WebContents::OnGetDefaultPrinter,
weak_factory_.GetWeakPtr(), std::move(settings),
std::move(callback), device_name, silent));

1
shell/browser/api/electron_api_web_contents.h
View file

@ -783,6 +783,7 @@ class WebContents : public gin::Wrappable<WebContents>,
DevToolsIndexingJobsMap devtools_indexing_jobs_;
scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
scoped_refptr<base::TaskRunner> print_task_runner_;
// Stores the frame thats currently in fullscreen, nullptr if there is none.
content::RenderFrameHost* fullscreen_frame_ = nullptr;