views/mus: Install a mus-friend ContextFactory for tests.

ui/compositor/test/fake_context_factory.cc

+// Copyright 2017 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 "ui/compositor/test/fake_context_factory.h"
+
+#include "base/threading/thread_task_runner_handle.h"
+#include "cc/output/compositor_frame.h"
+#include "cc/output/compositor_frame_sink_client.h"
+#include "cc/scheduler/begin_frame_source.h"
+#include "cc/scheduler/delay_based_time_source.h"
+#include "cc/test/fake_compositor_frame_sink.h"
+
+namespace ui {
+
+const cc::CompositorFrame& FakeContextFactory::GetLastCompositorFrame() const {
+  return *frame_sink_->last_sent_frame();
+}
+
+void FakeContextFactory::CreateCompositorFrameSink(
+    base::WeakPtr<ui::Compositor> compositor) {
+  auto frame_sink = cc::FakeCompositorFrameSink::Create3d();
+  frame_sink_ = frame_sink.get();
+  compositor->SetCompositorFrameSink(std::move(frame_sink));
+}
+
+scoped_refptr<cc::ContextProvider>
+FakeContextFactory::SharedMainThreadContextProvider() {
+  return nullptr;
+}
+
+void FakeContextFactory::RemoveCompositor(ui::Compositor* compositor) {
+  frame_sink_ = nullptr;
+}
+
+bool FakeContextFactory::DoesCreateTestContexts() {
+  return true;
+}
+
+uint32_t FakeContextFactory::GetImageTextureTarget(gfx::BufferFormat format,
+                                                   gfx::BufferUsage usage) {
+  return GL_TEXTURE_2D;
+}
+
+gpu::GpuMemoryBufferManager* FakeContextFactory::GetGpuMemoryBufferManager() {
+  return &gpu_memory_buffer_manager_;
+}
+
+cc::TaskGraphRunner* FakeContextFactory::GetTaskGraphRunner() {
+  return &task_graph_runner_;
+}
+
+void FakeContextFactory::AddObserver(ui::ContextFactoryObserver* observer) {}

[danakj, 2017/03/17 16:54:31]

(you can leave the defn of empty methods in the header if u want. this is fine
too)

[sadrul, 2017/03/17 18:59:14]

Done.

+void FakeContextFactory::RemoveObserver(ui::ContextFactoryObserver* observer) {}
+
+}  // namespace ui