blimp: Add support for input handling

blimp/client/input/blimp_input_manager.h

Index: blimp/client/input/blimp_input_manager.h
diff --git a/blimp/client/input/blimp_input_manager.h b/blimp/client/input/blimp_input_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..db4202e8ec6a4aa4059b0281a537279273fe748b
--- /dev/null
+++ b/blimp/client/input/blimp_input_manager.h
@@ -0,0 +1,132 @@
+// Copyright 2015 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_INPUT_BLIMP_INPUT_MANAGER_H_
+#define BLIMP_CLIENT_INPUT_BLIMP_INPUT_MANAGER_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "base/synchronization/waitable_event.h"
+#include "third_party/WebKit/public/web/WebInputEvent.h"
+#include "ui/events/blink/input_handler_proxy.h"
+#include "ui/events/blink/input_handler_proxy_client.h"
+#include "ui/events/gesture_detection/filtered_gesture_provider.h"
+#include "ui/events/gesture_detection/motion_event.h"
+
+namespace blimp {
+
+class BlimpInputManagerClient {
+ public:
+  virtual void SendWebInputEvent(
+      const blink::WebInputEvent& input_event) = 0;
+};
+
+// The BlimpInputManager handles input events for a specific render widget. The
+// class processes ui::events to generate web input events which are forwarded
+// to the compositor to be handled on the compositor thread. If the event can
+// not be handled locally by the compositor, it is given to the
+// BlimpInputManagerClient to be sent to the engine.
+//
+// The BlimpInputManager is created and destroyed on the main thread but can be
+// called from the main or compositor thread. It is safe for the
+// BlimpInputManager to be called on the compositor thread because:
+// 1) The only compositor threaded callers of the BlimpInputManager are the
+// BlimpInputManager itself.
+// 2) BlimpInputManager blocks the main thread to ensure the compositor-thread

[David Trainor- moved to gerrit, 2015/12/03 16:14:04]

Can you be a little more explicit that this is blocking the main thread to flush
all posted tasks to the compositor thread?

[Khushal, 2015/12/04 21:54:51]

Done.

+// teardown in its dtor, so there is no risk of any queued tasks calling it on
+// the compositor thread after it has been deleted on the main thread.
+class BlimpInputManager : public ui::InputHandlerProxyClient,
+                          public ui::GestureProviderClient {
+ public:
+  static scoped_ptr<BlimpInputManager> Create(
+      BlimpInputManagerClient* client,
+      scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> compositor_task_runner,
+      const base::WeakPtr<cc::InputHandler>& input_handler);
+
+  ~BlimpInputManager();
+
+  // Called to process a ui::MotionEvent. Returns true if the event was
+  // successfully processed.
+  bool OnTouchEvent(const ui::MotionEvent& motion_event);
+
+ private:
+  struct MainThreadOnly {
+    BlimpInputManagerClient* client;
+    ui::FilteredGestureProvider gesture_provider;
+
+    base::WeakPtrFactory<BlimpInputManager> weak_factory;
+
+    MainThreadOnly(
+        BlimpInputManagerClient* client,
+        BlimpInputManager* input_manager);
+    ~MainThreadOnly();
+  };
+
+  struct CompositorThreadOnly {
+    scoped_ptr<ui::InputHandlerProxy> input_handler_proxy;
+
+    // Used to queue calls to the BlimpInputManager to be run on the main
+    // thread. This ensures that any tasks queued are abandoned after the
+    // BlimpInputManager is destroyed.
+    base::WeakPtr<BlimpInputManager> input_manager_weak_ptr;
+
+    CompositorThreadOnly();
+    ~CompositorThreadOnly();
+  };
+
+  BlimpInputManager(
+      BlimpInputManagerClient* client,
+      scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> compositor_task_runner,
+      const base::WeakPtr<cc::InputHandler>& input_handler);
+
+
+  // InputHandlerProxyClient implementation. Called on the compositor thread.
+  void WillShutdown() override;
+  void TransferActiveWheelFlingAnimation(
+      const blink::WebActiveWheelFlingParameters& params) override;
+  blink::WebGestureCurve* CreateFlingAnimationCurve(
+      blink::WebGestureDevice device_source,
+      const blink::WebFloatPoint& velocity,
+      const blink::WebSize& cumulative_scroll) override;
+  void DidOverscroll(const gfx::Vector2dF& accumulated_overscroll,
+                     const gfx::Vector2dF& latest_overscroll_delta,
+                     const gfx::Vector2dF& current_fling_velocity,
+                     const gfx::PointF& causal_event_viewport_point) override;
+  void DidStopFlinging() override;
+  void DidAnimateForInput() override;
+
+  // ui::GestureProviderClient implementation. Called on main thread.
+  void OnGestureEvent(const ui::GestureEventData& gesture) override;
+
+  void CreateInputHandlerProxyOnCompositorThread(
+      base::WeakPtr<BlimpInputManager> input_manager_weak_ptr,
+      const base::WeakPtr<cc::InputHandler>& input_handler);
+  void HandleWebInputEventOnCompositorThread(
+      const blink::WebInputEvent& input_event);
+  void ShutdownOnCompositorThread(base::WaitableEvent* shutdown_event);
+  void SendWebInputEvent(const blink::WebInputEvent& input_event);
+
+  bool IsMainThread() const;
+  bool IsCompositorThread() const;
+
+  scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> compositor_task_runner_;
+
+  bool main_thread_blocked_;

[David Trainor- moved to gerrit, 2015/12/03 16:14:04]

Can you put a comment on how/where this is expected to be accessed?

[Khushal, 2015/12/04 21:54:51]

Done. Though, I'm not sure if its necessary. We could just add a test for this.

+
+  MainThreadOnly main_thread_vars_unsafe_;
+  MainThreadOnly& main();
+
+  CompositorThreadOnly compositor_thread_vars_unsafe_;
+  CompositorThreadOnly& compositor();
+
+  DISALLOW_COPY_AND_ASSIGN(BlimpInputManager);
+};
+
+}  // namespace blimp
+
+#endif  // BLIMP_CLIENT_INPUT_BLIMP_INPUT_MANAGER_H_