List printers managed by extensions in print preview

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

Index: chrome/browser/ui/webui/print_preview/print_preview_handler.cc
diff --git a/chrome/browser/ui/webui/print_preview/print_preview_handler.cc b/chrome/browser/ui/webui/print_preview/print_preview_handler.cc
index 335e6083faa72754eed0543e151c3244f205b2d6..44e2d04f730c9d0f4995edf31e7a12b8e6f0b8ef 100644
--- a/chrome/browser/ui/webui/print_preview/print_preview_handler.cc
+++ b/chrome/browser/ui/webui/print_preview/print_preview_handler.cc
@@ -89,6 +89,10 @@
 #include "chrome/browser/local_discovery/privet_constants.h"
 #endif
 
+#if defined(ENABLE_EXTENSIONS)
+#include "extensions/browser/api/printer_provider/printer_provider_api.h"
+#endif
+
 using content::BrowserThread;
 using content::RenderViewHost;
 using content::WebContents;
@@ -647,6 +651,14 @@ void PrintPreviewHandler::RegisterMessages() {
   web_ui()->RegisterMessageCallback("getPrivetPrinterCapabilities",
       base::Bind(&PrintPreviewHandler::HandleGetPrivetPrinterCapabilities,
                  base::Unretained(this)));
+  web_ui()->RegisterMessageCallback(
+      "getExtensionPrinters",
+      base::Bind(&PrintPreviewHandler::HandleGetExtensionPrinters,
+                 base::Unretained(this)));
+  web_ui()->RegisterMessageCallback(
+      "getExtensionPrinterCapabilities",
+      base::Bind(&PrintPreviewHandler::HandleGetExtensionPrinterCapabilities,
+                 base::Unretained(this)));
   RegisterForMergeSession();
 }
 
@@ -706,6 +718,46 @@ void PrintPreviewHandler::HandleGetPrivetPrinterCapabilities(
 #endif
 }
 
+void PrintPreviewHandler::HandleGetExtensionPrinters(
+    const base::ListValue* args) {
+#if defined(ENABLE_EXTENSIONS)
+  // TODO(tbarzic): Handle case where a new search is initiated before the
+  // previous one finishes. Currently, in this case Web UI layer may get
+  // multiple events with printer list from some extensions, and it may get
+  // fooled by |done| flag from the first search into marking the search
+  // complete.
+  extensions::PrinterProviderAPI::GetFactoryInstance()
+      ->Get(preview_web_contents()->GetBrowserContext())
+      ->DispatchGetPrintersRequested(
+          base::Bind(&PrintPreviewHandler::OnGotPrintersForExtension,
+                     weak_factory_.GetWeakPtr()));
+#else
+  OnGotPrintersForExtension(base::ListValue(), true /* done */);
+#endif
+}
+
+void PrintPreviewHandler::HandleGetExtensionPrinterCapabilities(
+    const base::ListValue* args) {
+  std::string extension_id;
+  std::string printer_id;
+  bool ok = true;
+  ok = ok && args->GetString(0, &extension_id);

[Vitaly Buka (NO REVIEWS), 2015/02/03 16:55:48]

bool ok = GetString(extension_id)
DCHECK(ok)

ok = GetString(printer_id)
DCHECK(ok)

+  ok = ok && args->GetString(1, &printer_id);
+  DCHECK(ok);
+
+#if defined(ENABLE_EXTENSIONS)
+  extensions::PrinterProviderAPI::GetFactoryInstance()
+      ->Get(preview_web_contents()->GetBrowserContext())
+      ->DispatchGetCapabilityRequested(
+          extension_id, printer_id,
+          base::Bind(&PrintPreviewHandler::OnGotExtensionPrinterCapabilities,
+                     weak_factory_.GetWeakPtr(), extension_id, printer_id));
+#else
+  OnGotExtensionPrinterCapabilities(extension_id, printer_id,
+                                    base::DictionaryValue());
+#endif
+}
+
 void PrintPreviewHandler::HandleGetPreview(const base::ListValue* args) {
   DCHECK_EQ(3U, args->GetSize());
   scoped_ptr<base::DictionaryValue> settings(GetSettingsDictionary(args));
@@ -1588,6 +1640,23 @@ void PrintPreviewHandler::FillPrinterDescription(
 
 #endif  // defined(ENABLE_SERVICE_DISCOVERY)
 
+void PrintPreviewHandler::OnGotPrintersForExtension(
+    const base::ListValue& printers,
+    bool done) {
+  web_ui()->CallJavascriptFunction("onExtensionPrintersAdded", printers,
+                                   base::FundamentalValue(done));
+}
+
+void PrintPreviewHandler::OnGotExtensionPrinterCapabilities(
+    const std::string& extension_id,
+    const std::string& printer_id,
+    const base::DictionaryValue& capabilities) {
+  web_ui()->CallJavascriptFunction("onExtensionCapabilitiesSet",
+                                   base::StringValue(extension_id),
+                                   base::StringValue(printer_id),

[Vitaly Buka (NO REVIEWS), 2015/02/03 16:55:48]

consider merging them here and use single string as ID on js side.

[tbarzic, 2015/02/03 17:07:27]

I had a similar idea. The main reason these are merged to a single id on js side
is that extension id is needed to create initially (auto) selected destination
in case it's an extension destination. This means that webui layer would have to
know how to parse the extension id from the destination id saved in the app
state (and I'd rather have this logic both in natie and webui layer).

I guess this could be solved by adding extension id field to app state. wdyt?

+                                   capabilities);
+}
+
 void PrintPreviewHandler::RegisterForMergeSession() {
   DCHECK(!reconcilor_);
   Profile* profile = Profile::FromWebUI(web_ui());