Add a full Blimp integration test.

blimp/engine/browser_tests/blimp_contents_view_readback_helper.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 "blimp/engine/browser_tests/blimp_contents_view_readback_helper.h"
+
+#include "base/bind.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+
+namespace blimp {
+
+BlimpContentsViewReadbackHelper::BlimpContentsViewReadbackHelper()
+    : event_(base::WaitableEvent::ResetPolicy::MANUAL,
+             base::WaitableEvent::InitialState::NOT_SIGNALED),
+      weak_ptr_factory_(this) {}
+
+BlimpContentsViewReadbackHelper::~BlimpContentsViewReadbackHelper() = default;
+
+client::BlimpContentsView::ReadbackRequestCallback
+BlimpContentsViewReadbackHelper::GetCallback() {
+  return base::Bind(&BlimpContentsViewReadbackHelper::OnReadbackComplete,
+                    weak_ptr_factory_.GetWeakPtr());
+}
+
+SkBitmap* BlimpContentsViewReadbackHelper::GetBitmap() const {
+  return bitmap_.get();
+}
+
+void BlimpContentsViewReadbackHelper::OnReadbackComplete(
+    std::unique_ptr<SkBitmap> bitmap) {
+  bitmap_ = std::move(bitmap);
+  event_.Signal();
+}
+
+}  // namespace blimp