Add a PrinterDiscoverer fake object.

chromeos/printing/fake_printer_detector.cc

+// Copyright 2016 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 "chromeos/printing/fake_printer_detector.h"
+
+#include <algorithm>
+#include <iterator>
+#include <memory>
+
+#include "base/bind.h"
+#include "base/memory/ptr_util.h"
+#include "base/strings/stringprintf.h"
+#include "base/threading/sequenced_task_runner_handle.h"
+#include "base/time/time.h"
+#include "chromeos/printing/printer_detector.h"
+
+namespace chromeos {
+
+// static
+std::unique_ptr<PrinterDetector> PrinterDetector::Create() {
+  return base::MakeUnique<FakePrinterDetector>();
+}
+
+FakePrinterDetector::~FakePrinterDetector() {}
+
+bool FakePrinterDetector::StartDiscovery() {
+  discovery_running_ = true;
+  base::SequencedTaskRunnerHandle::Get()->PostNonNestableDelayedTask(
+      FROM_HERE, base::Bind(&FakePrinterDetector::EmitPrinters,
+                            weak_ptr_factory_.GetWeakPtr(), 0, 2),
+      base::TimeDelta::FromMilliseconds(2000));
+  return true;
+}
+
+bool FakePrinterDetector::StopDiscovery() {
+  discovery_running_ = false;
+  return true;
+}
+
+void FakePrinterDetector::AddObserver(PrinterDetector::Observer* observer) {
+  observers_.push_back(observer);
+}
+
+void FakePrinterDetector::RemoveObserver(PrinterDetector::Observer* observer) {
+  auto found = std::find(observers_.begin(), observers_.end(), observer);
+  if (found != observers_.end())
+    observers_.erase(found);
+}
+
+FakePrinterDetector::FakePrinterDetector()
+    : discovery_running_(false), weak_ptr_factory_(this) {
+  for (int i = 0; i < 12; i++) {
+    // printer doesn't have a ppd
+    printers_.emplace_back(base::StringPrintf("GUID%2d", i));
+    printers_[i].set_display_name(base::StringPrintf("PrinterName%2d", i));
+    printers_[i].set_description(
+        base::StringPrintf("Printer%2dDescription", i));
+    printers_[i].set_manufacturer("Chromium");
+    printers_[i].set_model(i % 3 == 0 ? "Inkjet" : "Laser Maker");
+    printers_[i].set_uri(
+        base::StringPrintf("lpr://192.168.1.%d:9100/bldg/printer", i));
+    printers_[i].set_uuid(
+        base::StringPrintf("UUID-%4d-%4d-%4d-UUID", i * 3, i * 2, i));
+  }
+}
+
+void FakePrinterDetector::EmitPrinters(size_t start, size_t end) {
+  if (!discovery_running_)
+    return;
+
+  size_t clipped_end = std::min(printers_.size(), end);

[Carlson, 2016/10/03 18:00:51]

If you're making end "safe", you should probably do the same for start.

[skau, 2016/10/03 22:57:26]

Done.

+  if (!observers_.empty()) {
+    auto start_iter = printers_.begin();
+    std::advance(start_iter, start);
+    auto end_iter = printers_.begin();
+    std::advance(end_iter, clipped_end);
+    std::vector<Printer> subset(start_iter, end_iter);

[Carlson, 2016/10/03 18:00:51]

I think the above can just be simplified to

std::vector<Printer> subset(printers_.begin() + start, 
                            printers_.begin() + clipped_end);

?

[skau, 2016/10/03 22:57:26]

Done.

+    for (auto observer : observers_)
+      observer->OnPrintersFound(subset);
+  }
+
+  if (end < printers_.size()) {

[Carlson, 2016/10/03 18:00:51]

This deserved a comment, I think.

[skau, 2016/10/03 22:57:26]

Done.

+    base::SequencedTaskRunnerHandle::Get()->PostNonNestableDelayedTask(
+        FROM_HERE,
+        base::Bind(&FakePrinterDetector::EmitPrinters,
+                   weak_ptr_factory_.GetWeakPtr(), clipped_end, end + end),
+        base::TimeDelta::FromMilliseconds(2000));
+  }
+}
+
+}  // namespace chromeos