Move compositor thread input handling logic into content

content/renderer/gpu/input_handler_proxy.h

+// Copyright (c) 2013 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 CONTENT_RENDERER_GPU_INPUT_HANDLER_PROXY_H_
+#define CONTENT_RENDERER_GPU_INPUT_HANDLER_PROXY_H_
+
+#include "base/basictypes.h"
+#include "base/hash_tables.h"
+#include "base/memory/scoped_ptr.h"
+#include "cc/input/input_handler.h"
+#include "content/common/content_export.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebGestureCurve.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebGestureCurveTarget.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebActiveWheelFlingParameters.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebInputEvent.h"
+
+namespace content {
+
+class InputHandlerProxyClient;
+
+class CONTENT_EXPORT InputHandlerProxy

[danakj, 2013/05/06 16:33:39]

It took me a while to figure out these things are all on the impl thread - i got
there from a comment in the InputMessageHandler's header.

Could we document that here too with a class-level comment of some sort?

It's especially confusing because of all the webkit types and overrides.

+    : public cc::InputHandlerClient,
+      public NON_EXPORTED_BASE(WebKit::WebGestureCurveTarget) {
+ public:
+  explicit InputHandlerProxy(cc::InputHandler* input_handler);
+  virtual ~InputHandlerProxy();
+
+  void SetClient(InputHandlerProxyClient* client);
+  void HandleInputEvent(const WebKit::WebInputEvent& event);
+
+  // cc::InputHandlerClient implementation.
+  virtual void Animate(base::TimeTicks time) OVERRIDE;
+  virtual void MainThreadHasStoppedFlinging() OVERRIDE;
+
+  // WebKit::WebGestureCurveTarget implementation.
+  virtual void scrollBy(const WebKit::WebFloatSize& offset);
+  virtual void notifyCurrentFlingVelocity(const WebKit::WebFloatSize& velocity);
+
+  bool gesture_scroll_on_impl_thread_for_testing() const {
+    return gesture_scroll_on_impl_thread_;
+  }
+
+ private:
+  enum EventDisposition {
+    DidHandle,
+    DidNotHandle,
+    DropEvent
+  };
+  // This function processes the input event and determines the disposition, but
+  // does not make any calls out to the InputHandlerProxyClient. Some input
+  // types defer to helpers.
+  EventDisposition HandleInputEventInternal(const WebKit::WebInputEvent& event);
+
+  EventDisposition HandleGestureFling(const WebKit::WebGestureEvent& event);
+
+  // Returns true if we scrolled by the increment.
+  bool TouchpadFlingScroll(const WebKit::WebFloatSize& increment);
+
+  // Returns true if we actually had an active fling to cancel.
+  bool CancelCurrentFling();
+
+  scoped_ptr<WebKit::WebGestureCurve> fling_curve_;
+  // Parameters for the active fling animation, stored in case we need to
+  // transfer it out later.
+  WebKit::WebActiveWheelFlingParameters fling_parameters_;
+
+  InputHandlerProxyClient* client_;
+  cc::InputHandler* input_handler_;
+
+#ifndef NDEBUG
+  bool expect_scroll_update_end_;
+  bool expect_pinch_update_end_;
+#endif
+  bool gesture_scroll_on_impl_thread_;
+  bool gesture_pinch_on_impl_thread_;
+  // This is always false when there are no flings on the main thread, but
+  // conservative in the sense that we might not be actually flinging when it is
+  // true.
+  bool fling_active_on_main_thread_;

[danakj, 2013/05/06 16:33:39]

fling_may_be_active_on_main_thread_ ?

+
+  DISALLOW_COPY_AND_ASSIGN(InputHandlerProxy);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_GPU_INPUT_HANDLER_PROXY_H_