[DesktopCapturer] FallbackDesktopCapturerWrapper and its tests

webrtc/modules/desktop_capture/fallback_desktop_capturer_wrapper.cc

Index: webrtc/modules/desktop_capture/fallback_desktop_capturer_wrapper.cc
diff --git a/webrtc/modules/desktop_capture/fallback_desktop_capturer_wrapper.cc b/webrtc/modules/desktop_capture/fallback_desktop_capturer_wrapper.cc
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index 0000000000000000000000000000000000000000..e8762ada110ca3c04bdea702547cf4f9cfa14daf
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+++ b/webrtc/modules/desktop_capture/fallback_desktop_capturer_wrapper.cc
@@ -0,0 +1,159 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/desktop_capture/fallback_desktop_capturer_wrapper.h"
+
+#include <utility>
+
+#include "webrtc/base/checks.h"
+
+namespace webrtc {
+
+namespace {
+
+// Implementation to share a SharedMemoryFactory between DesktopCapturer
+// instances. This class is designed for synchronized DesktopCapturer
+// implementations only.
+class SharedMemoryFactoryProxy : public SharedMemoryFactory {
+ public:
+  // Users should maintain the lifetime of |factory| to ensure it overlives
+  // current instance.
+  static std::unique_ptr<SharedMemoryFactory> Create(
+      SharedMemoryFactory* factory);
+  ~SharedMemoryFactoryProxy() override;
+
+  // Forwards CreateSharedMemory() calls to |factory_|. Users should always call
+  // this function in one thread. Users should not call this function after the
+  // SharedMemoryFactory which current instance created from has been destroyed.
+  std::unique_ptr<SharedMemory> CreateSharedMemory(size_t size) override;
+
+ private:
+  explicit SharedMemoryFactoryProxy(SharedMemoryFactory* factory);
+
+  SharedMemoryFactory* factory_ = nullptr;
+  rtc::ThreadChecker thread_checker_;
+};
+
+}  // namespace
+
+SharedMemoryFactoryProxy::SharedMemoryFactoryProxy(
+    SharedMemoryFactory* factory) {
+  RTC_DCHECK(factory);
+  factory_ = factory;
+}
+
+// static
+std::unique_ptr<SharedMemoryFactory>
+SharedMemoryFactoryProxy::Create(SharedMemoryFactory* factory) {
+  return std::unique_ptr<SharedMemoryFactory>(
+      new SharedMemoryFactoryProxy(factory));
+}
+
+SharedMemoryFactoryProxy::~SharedMemoryFactoryProxy() = default;
+
+std::unique_ptr<SharedMemory>
+SharedMemoryFactoryProxy::CreateSharedMemory(size_t size) {
+  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  return factory_->CreateSharedMemory(size);
+}
+
+FallbackDesktopCapturerWrapper::FallbackDesktopCapturerWrapper(
+    std::unique_ptr<DesktopCapturer> main_capturer,
+    std::unique_ptr<DesktopCapturer> secondary_capturer)
+    : main_capturer_(std::move(main_capturer)),
+      secondary_capturer_(std::move(secondary_capturer)) {
+  RTC_DCHECK(main_capturer_);
+  RTC_DCHECK(secondary_capturer_);
+}
+
+FallbackDesktopCapturerWrapper::~FallbackDesktopCapturerWrapper() = default;
+
+void FallbackDesktopCapturerWrapper::Start(
+    DesktopCapturer::Callback* callback) {
+  // FallbackDesktopCapturerWrapper catchs the callback of the main capturer,
+  // and checks its return value to decide whether the secondary capturer should
+  // be involved.
+  main_capturer_->Start(this);
+  // For the secondary capturer, we do not have a backup plan anymore, so
+  // FallbackDesktopCapturerWrapper won't check its return value any more. It
+  // will directly return to the input |callback|.
+  secondary_capturer_->Start(callback);
+  callback_ = callback;
+}
+
+void FallbackDesktopCapturerWrapper::SetSharedMemoryFactory(
+    std::unique_ptr<SharedMemoryFactory> shared_memory_factory) {
+  shared_memory_factory_ = std::move(shared_memory_factory);
+  if (shared_memory_factory_) {
+    main_capturer_->SetSharedMemoryFactory(
+        SharedMemoryFactoryProxy::Create(shared_memory_factory_.get()));
+    secondary_capturer_->SetSharedMemoryFactory(
+        SharedMemoryFactoryProxy::Create(shared_memory_factory_.get()));
+  } else {
+    main_capturer_->SetSharedMemoryFactory(
+        std::unique_ptr<SharedMemoryFactory>());
+    secondary_capturer_->SetSharedMemoryFactory(
+        std::unique_ptr<SharedMemoryFactory>());
+  }
+}
+
+void FallbackDesktopCapturerWrapper::CaptureFrame() {
+  RTC_DCHECK(callback_);
+  if (main_capturer_permanent_error_) {
+    secondary_capturer_->CaptureFrame();
+  } else {
+    main_capturer_->CaptureFrame();
+  }
+}
+
+void FallbackDesktopCapturerWrapper::SetExcludedWindow(WindowId window) {
+  main_capturer_->SetExcludedWindow(window);
+  secondary_capturer_->SetExcludedWindow(window);
+}
+
+bool FallbackDesktopCapturerWrapper::GetSourceList(SourceList* sources) {
+  if (main_capturer_permanent_error_) {
+    return secondary_capturer_->GetSourceList(sources);
+  }
+  return main_capturer_->GetSourceList(sources);
+}
+
+bool FallbackDesktopCapturerWrapper::SelectSource(SourceId id) {
+  if (main_capturer_permanent_error_) {
+    return secondary_capturer_->SelectSource(id);
+  }
+  return main_capturer_->SelectSource(id) &&
+         secondary_capturer_->SelectSource(id);
+}
+
+bool FallbackDesktopCapturerWrapper::FocusOnSelectedSource() {
+  if (main_capturer_permanent_error_) {
+    return secondary_capturer_->FocusOnSelectedSource();
+  }
+  return main_capturer_->FocusOnSelectedSource() ||
+         secondary_capturer_->FocusOnSelectedSource();
+}
+
+void FallbackDesktopCapturerWrapper::OnCaptureResult(
+    Result result,
+    std::unique_ptr<DesktopFrame> frame) {
+  RTC_DCHECK(callback_);
+  if (result == Result::SUCCESS) {
+    callback_->OnCaptureResult(result, std::move(frame));
+    return;
+  }
+
+  if (result == Result::ERROR_PERMANENT) {
+    main_capturer_permanent_error_ = true;
+  }
+  secondary_capturer_->CaptureFrame();
+}
+
+}  // namespace webrtc