Pass list of printers to chrome using file.

chrome/browser/extensions/api/cloud_print_private/cloud_print_private_api.cc

Index: chrome/browser/extensions/api/cloud_print_private/cloud_print_private_api.cc
diff --git a/chrome/browser/extensions/api/cloud_print_private/cloud_print_private_api.cc b/chrome/browser/extensions/api/cloud_print_private/cloud_print_private_api.cc
index 37ca794d1e530ac666202d5398cdf56041f1ea9c..3a3d4676eb6a77681be3ac63b402268ca06c5cfb 100644
--- a/chrome/browser/extensions/api/cloud_print_private/cloud_print_private_api.cc
+++ b/chrome/browser/extensions/api/cloud_print_private/cloud_print_private_api.cc
@@ -6,9 +6,13 @@
 
 #include <string>
 
+#include "base/command_line.h"
+#include "base/file_util.h"
+#include "base/json/json_reader.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/printing/cloud_print/cloud_print_proxy_service.h"
 #include "chrome/browser/printing/cloud_print/cloud_print_proxy_service_factory.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/api/cloud_print_private.h"
 #include "google_apis/google_api_keys.h"
 #include "net/base/net_util.h"
@@ -91,20 +95,38 @@ void CloudPrintPrivateGetPrintersFunction::ReturnResult(
 }
 
 void CloudPrintPrivateGetPrintersFunction::CollectPrinters() {
-  scoped_ptr<base::ListValue> result(new base::ListValue());
-  if (CloudPrintTestsDelegate::instance()) {
-    std::vector<std::string> printers =
-        CloudPrintTestsDelegate::instance()->GetPrinters();
-    for (size_t i = 0; i < printers.size(); ++i)
-      result->Append(Value::CreateStringValue(printers[i]));
+  scoped_ptr<base::ListValue> result;
+
+  CommandLine* command_line = CommandLine::ForCurrentProcess();
+  base::FilePath list_path(
+      command_line->GetSwitchValuePath(switches::kCloudPrintAddPrinters));
+  if (!list_path.empty()) {
+    std::string printers_json;
+    file_util::ReadFileToString(list_path, &printers_json);
+    scoped_ptr<Value> value(base::JSONReader::Read(printers_json));
+    base::ListValue* list = NULL;
+    if (value)
+      value->GetAsList(&list);
+    if (list) {
+      result.reset(list);
+      value.release();  // Holds the same object as result.
+    }
   } else {
-    printing::PrinterList printers;
-    scoped_refptr<printing::PrintBackend> backend(
-      printing::PrintBackend::CreateInstance(NULL));
-    if (backend)
-      backend->EnumeratePrinters(&printers);
-    for (size_t i = 0; i < printers.size(); ++i)
-      result->Append(Value::CreateStringValue(printers[i].printer_name));
+    result.reset(new base::ListValue());
+    if (CloudPrintTestsDelegate::instance()) {
+      std::vector<std::string> printers =
+          CloudPrintTestsDelegate::instance()->GetPrinters();
+      for (size_t i = 0; i < printers.size(); ++i)
+        result->Append(Value::CreateStringValue(printers[i]));
+    } else {
+      printing::PrinterList printers;
+      scoped_refptr<printing::PrintBackend> backend(
+        printing::PrintBackend::CreateInstance(NULL));
+      if (backend)
+        backend->EnumeratePrinters(&printers);
+      for (size_t i = 0; i < printers.size(); ++i)
+        result->Append(Value::CreateStringValue(printers[i].printer_name));
+    }
   }
   content::BrowserThread::PostTask(content::BrowserThread::UI, FROM_HERE,
       base::Bind(&CloudPrintPrivateGetPrintersFunction::ReturnResult, this,