Mac: Coalesce scroll events.

chrome/browser/renderer_host/render_widget_host_unittest.cc

 // Copyright (c) 2009 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 "app/gfx/canvas.h"
 #include "base/basictypes.h"
 #include "base/keyboard_codes.h"
 #include "base/scoped_ptr.h"
 #include "base/shared_memory.h"
 #include "build/build_config.h"
 #include "chrome/browser/renderer_host/backing_store.h"
 #include "chrome/browser/renderer_host/test/test_render_view_host.h"
 #include "chrome/common/render_messages.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using WebKit::WebInputEvent;
+using WebKit::WebMouseWheelEvent;
 
 // RenderWidgetHostProcess -----------------------------------------------------
 
 class RenderWidgetHostProcess : public MockRenderProcessHost {
  public:
   explicit RenderWidgetHostProcess(Profile* profile)
       : MockRenderProcessHost(profile),
         current_update_buf_(NULL),
         update_msg_should_reply_(false),
         update_msg_reply_flags_(0) {
@@ skipping 85 matching lines @@
   // RenderWidgetHostView override.
   virtual gfx::Rect GetViewBounds() const {
     return bounds_;
   }
 
  protected:
   gfx::Rect bounds_;
   DISALLOW_COPY_AND_ASSIGN(TestView);
 };
 
-// MockRenderWidgetHostTest ----------------------------------------------------
+// MockRenderWidgetHost ----------------------------------------------------
 
 class MockRenderWidgetHost : public RenderWidgetHost {
  public:
   MockRenderWidgetHost(RenderProcessHost* process, int routing_id)
       : RenderWidgetHost(process, routing_id),
         prehandle_keyboard_event_(false),
         prehandle_keyboard_event_called_(false),
         prehandle_keyboard_event_type_(WebInputEvent::Undefined),
         unhandled_keyboard_event_called_(false),
         unhandled_keyboard_event_type_(WebInputEvent::Undefined) {
@@ skipping 80 matching lines @@
     host_->OnMessageReceived(*response);
   }
 
   void SimulateKeyboardEvent(WebInputEvent::Type type) {
     NativeWebKeyboardEvent key_event;
     key_event.type = type;
     key_event.windowsKeyCode = base::VKEY_L;  // non-null made up value.
     host_->ForwardKeyboardEvent(key_event);
   }
 
+  void SimulateWheelEvent(float dX, float dY, int modifiers) {
+    WebMouseWheelEvent wheel_event;
+    wheel_event.type = WebInputEvent::MouseWheel;
+    wheel_event.deltaX = dX;
+    wheel_event.deltaY = dY;
+    wheel_event.modifiers = modifiers;
+    host_->ForwardWheelEvent(wheel_event);
+  }
+
   MessageLoopForUI message_loop_;
 
   scoped_ptr<TestingProfile> profile_;
   RenderWidgetHostProcess* process_;  // Deleted automatically by the widget.
   scoped_ptr<MockRenderWidgetHost> host_;
   scoped_ptr<TestView> view_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostTest);
 };
 
@@ skipping 316 matching lines @@
   EXPECT_EQ(ViewMsg_HandleInputEvent::ID,
             process_->sink().GetMessageAt(0)->type());
   process_->sink().ClearMessages();
 
   // Send the simulated response from the renderer back.
   SendInputEventACK(WebInputEvent::KeyUp, false);
 
   EXPECT_TRUE(host_->unhandled_keyboard_event_called());
   EXPECT_EQ(WebInputEvent::KeyUp, host_->unhandled_keyboard_event_type());
 }
+
+TEST_F(RenderWidgetHostTest, CoalescesWheelEvents) {
+  process_->sink().ClearMessages();
+
+  // Simulate wheel events.
+  SimulateWheelEvent(0, -5, 0);  // sent directly
+  SimulateWheelEvent(0, -10, 0);  // enqueued
+  SimulateWheelEvent(8, -6, 0);  // coalesced into previous event
+  SimulateWheelEvent(9, -7, 1);  // enqueued, different modifiers
+
+  // Check that only the first event was sent.
+  EXPECT_EQ(1U, process_->sink().message_count());
+  EXPECT_TRUE(process_->sink().GetUniqueMessageMatching(
+                  ViewMsg_HandleInputEvent::ID));
+  process_->sink().ClearMessages();
+
+  // Check that the ACK sends the second message.
+  SendInputEventACK(WebInputEvent::MouseWheel, true);
+  EXPECT_EQ(1U, process_->sink().message_count());
+  EXPECT_TRUE(process_->sink().GetUniqueMessageMatching(
+                  ViewMsg_HandleInputEvent::ID));
+  process_->sink().ClearMessages();
+
+  // One more time.
+  SendInputEventACK(WebInputEvent::MouseWheel, true);
+  EXPECT_EQ(1U, process_->sink().message_count());
+  EXPECT_TRUE(process_->sink().GetUniqueMessageMatching(
+                  ViewMsg_HandleInputEvent::ID));
+  process_->sink().ClearMessages();
+
+  // After the final ack, the queue should be empty.
+  SendInputEventACK(WebInputEvent::MouseWheel, true);
+  EXPECT_EQ(0U, process_->sink().message_count());
+}