Interrogate PpdProvider from PrintPreview.

chrome/browser/ui/webui/print_preview/printer_backend_proxy.cc

Index: chrome/browser/ui/webui/print_preview/printer_backend_proxy.cc
diff --git a/chrome/browser/ui/webui/print_preview/printer_backend_proxy.cc b/chrome/browser/ui/webui/print_preview/printer_backend_proxy.cc
index effbb06c0d45e3532ef7a9dc6ff37666ed58006a..104453a8a10745c1886e9c8b6a103ab7ba98d816 100644
--- a/chrome/browser/ui/webui/print_preview/printer_backend_proxy.cc
+++ b/chrome/browser/ui/webui/print_preview/printer_backend_proxy.cc
@@ -52,34 +52,41 @@ std::unique_ptr<base::DictionaryValue> FetchCapabilitiesOnBlockingPool(
   return GetSettingsOnBlockingPool(device_name, basic_info);
 }
 
-}  // namespace
-
-std::string GetDefaultPrinterOnBlockingPoolThread() {
-  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+class PrinterBackendProxyImpl : public PrinterBackendProxy {

[Carlson, 2016/12/02 19:10:22]

Maybe a better suffix here would be Chrome instead of Impl?  More orthogonal to
the ChromeOS version.  Also a short comment about what this class is would be
good.

[skau, 2016/12/05 23:13:34]

Renamed to 'Default'.  Chrome seems odd since ChromeOS isn't orthogonal to
Chrome.  ChromeOS is just special.

+ public:
+  std::string GetDefaultPrinterOnBlockingPoolThread() override {
+    DCHECK(
+        content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+
+    scoped_refptr<printing::PrintBackend> print_backend(
+        PrintBackend::CreateInstance(nullptr));
+
+    std::string default_printer = print_backend->GetDefaultPrinterName();
+    VLOG(1) << "Default Printer: " << default_printer;
+    return default_printer;
+  }
 
-  scoped_refptr<printing::PrintBackend> print_backend(
-      PrintBackend::CreateInstance(nullptr));
+  void EnumeratePrinters(const EnumeratePrintersCallback& cb) override {
+    base::PostTaskAndReplyWithResult(
+        content::BrowserThread::GetBlockingPool(), FROM_HERE,
+        base::Bind(&EnumeratePrintersOnBlockingPoolThread), cb);
+  }
 
-  std::string default_printer = print_backend->GetDefaultPrinterName();
-  VLOG(1) << "Default Printer: " << default_printer;
-  return default_printer;
-}
+  void ConfigurePrinterAndFetchCapabilities(
+      const std::string& device_name,
+      const PrinterSetupCallback& cb) override {
+    DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
-void EnumeratePrinters(Profile* /* profile */,
-                       const EnumeratePrintersCallback& cb) {
-  base::PostTaskAndReplyWithResult(
-      content::BrowserThread::GetBlockingPool(), FROM_HERE,
-      base::Bind(&EnumeratePrintersOnBlockingPoolThread), cb);
-}
+    base::PostTaskAndReplyWithResult(
+        content::BrowserThread::GetBlockingPool(), FROM_HERE,
+        base::Bind(&FetchCapabilitiesOnBlockingPool, device_name), cb);
+  }
+};
 
-void ConfigurePrinterAndFetchCapabilities(Profile* /* profile */,
-                                          const std::string& device_name,
-                                          const PrinterSetupCallback& cb) {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+}  // namespace
 
-  base::PostTaskAndReplyWithResult(
-      content::BrowserThread::GetBlockingPool(), FROM_HERE,
-      base::Bind(&FetchCapabilitiesOnBlockingPool, device_name), cb);
+std::unique_ptr<PrinterBackendProxy> PrinterBackendProxy::Create() {
+  return base::MakeUnique<PrinterBackendProxyImpl>();
 }
 
 }  // namespace printing