Expose Blimp dependencies to the embedder

blimp/client/public/compositor/compositor_dependencies.h

Index: blimp/client/public/compositor/compositor_dependencies.h
diff --git a/blimp/client/public/compositor/compositor_dependencies.h b/blimp/client/public/compositor/compositor_dependencies.h
new file mode 100644
index 0000000000000000000000000000000000000000..4c224c6487cc6b1632671d1e25882c481194a336
--- /dev/null
+++ b/blimp/client/public/compositor/compositor_dependencies.h
@@ -0,0 +1,46 @@
+// 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.
+
+#ifndef BLIMP_CLIENT_PUBLIC_COMPOSITOR_COMPOSITOR_DEPENDENCIES_H_
+#define BLIMP_CLIENT_PUBLIC_COMPOSITOR_COMPOSITOR_DEPENDENCIES_H_
+
+#include "base/callback.h"
+#include "base/memory/ptr_util.h"
+
+namespace cc {
+class ContextProvider;
+class LayerTreeSettings;
+class SurfaceManager;
+}  // namespace cc
+
+namespace gpu {
+class GpuMemoryBufferManager;
+}  // namespace gpu
+
+namespace blimp {
+namespace client {
+
+// A set of compositor dependencies that must be provided by the embedder.
+class CompositorDependencies {

[Khushal, 2016/08/25 05:02:54]

Comment on the lifetime? The Dependencies are expected to outlive all
BlimpContents?

[David Trainor- moved to gerrit, 2016/08/26 17:15:54]

Done.

+ public:
+  using ContextProviderCallback =

[Khushal, 2016/08/25 05:02:54]

The ui::ContextProviderFactory passes an enum saying why the failure, should we
mirror a subset of that here. I think except GPU_SURFACE_HANDLE loss, we can
expect all responses back, since we only need offscreen contexts, and that
response is for an onscreen one.

[David Trainor- moved to gerrit, 2016/08/26 17:15:54]

Huh that callback doesn't return an enum either.  Maybe I'm missing the code
path.  Could you tell me where it is?  Thanks!

[Khushal, 2016/08/26 19:34:25]

Ummm, that patch hasn't landed yet. My bad.

+      base::Callback<void(scoped_refptr<cc::ContextProvider>)>;
+
+  virtual ~CompositorDependencies() = default;
+
+  // Settings used to create all BlimpCompositor instances.
+  virtual std::unique_ptr<cc::LayerTreeSettings> GetLayerTreeSettings() = 0;
+  virtual gpu::GpuMemoryBufferManager* GetGpuMemoryBufferManager() = 0;
+  virtual cc::SurfaceManager* GetSurfaceManager() = 0;
+  virtual uint32_t AllocateSurfaceId() = 0;
+
+  // This call may return synchronously if the ContextProvider has already been
+  // created.  It may be asynchronous if it needs to build it though.

[Khushal, 2016/08/25 05:02:54]

nit: the asynchronous bit is expected.

[David Trainor- moved to gerrit, 2016/08/26 17:15:54]

Done.

+  virtual void GetContextProvider(const ContextProviderCallback& callback) = 0;
+};
+
+}  // namespace client
+}  // namespace blimp
+
+#endif  // BLIMP_CLIENT_PUBLIC_COMPOSITOR_COMPOSITOR_DEPENDENCIES_H_