Revert of Remove enable/disable wheel gestures setting.

content/browser/renderer_host/render_widget_host_view_mac_unittest.mm

 // Copyright (c) 2012 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 "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #include <Cocoa/Cocoa.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <tuple>
@@ skipping 248 matching lines @@
     RecycleAndWait();
 
     // See comment in SetUp().
     test_rvh()->GetWidget()->SetView(
         static_cast<RenderWidgetHostViewBase*>(old_rwhv_));
 
     ImageTransportFactory::Terminate();
     RenderViewHostImplTestHarness::TearDown();
   }
 
+  void SetupForWheelGestures(bool enable_wheel_gestures) {
+    CHECK(!base::CommandLine::ForCurrentProcess()->HasSwitch(
+        switches::kDisableWheelGestures));
+    CHECK(!base::CommandLine::ForCurrentProcess()->HasSwitch(
+        switches::kEnableWheelGestures));
+    base::CommandLine::ForCurrentProcess()->AppendSwitch(
+        enable_wheel_gestures ? switches::kEnableWheelGestures
+                              : switches::kDisableWheelGestures);
+    // Owned by its |cocoa_view()|, i.e. |rwhv_cocoa_|.
+    rwhv_mac_ = new RenderWidgetHostViewMac(rvh()->GetWidget(), false);
+    rwhv_cocoa_.reset([rwhv_mac_->cocoa_view() retain]);
+  }
+
   void RecycleAndWait() {
     pool_.Recycle();
     base::MessageLoop::current()->RunUntilIdle();
     pool_.Recycle();
   }
 
   void DestroyHostViewRetainCocoaView() {
     test_rvh()->GetWidget()->SetView(nullptr);
     rwhv_mac_->Destroy();
   }
@@ skipping 634 matching lines @@
   // render view receives it.
   NSEvent* event2 = MockScrollWheelEventWithPhase(@selector(phaseEnded), 0);
   [NSApp postEvent:event2 atStart:NO];
   base::MessageLoop::current()->RunUntilIdle();
   ASSERT_EQ(2U, process_host->sink().message_count());
 
   // Clean up.
   host->ShutdownAndDestroyWidget(true);
 }
 
+TEST_F(RenderWidgetHostViewMacTest, IgnoreEmptyUnhandledWheelEvent) {
+  SetupForWheelGestures(false);
+
+  // Initialize the view associated with a MockRenderWidgetHostImpl, rather than
+  // the MockRenderProcessHost that is set up by the test harness which mocks
+  // out |OnMessageReceived()|.
+  TestBrowserContext browser_context;
+  MockRenderProcessHost* process_host =
+      new MockRenderProcessHost(&browser_context);
+  process_host->Init();
+  MockRenderWidgetHostDelegate delegate;
+  int32_t routing_id = process_host->GetNextRoutingID();
+  MockRenderWidgetHostImpl* host =
+      new MockRenderWidgetHostImpl(&delegate, process_host, routing_id);
+  RenderWidgetHostViewMac* view = new RenderWidgetHostViewMac(host, false);
+  process_host->sink().ClearMessages();
+
+  // Add a delegate to the view.
+  base::scoped_nsobject<MockRenderWidgetHostViewMacDelegate> view_delegate(
+      [[MockRenderWidgetHostViewMacDelegate alloc] init]);
+  view->SetDelegate(view_delegate.get());
+
+  // Send an initial wheel event for scrolling by 3 lines.
+  NSEvent* event1 = MockScrollWheelEventWithPhase(@selector(phaseBegan), 3);
+  [view->cocoa_view() scrollWheel:event1];
+  ASSERT_EQ(1U, process_host->sink().message_count());
+  process_host->sink().ClearMessages();
+
+  // Indicate that the wheel event was unhandled.
+  InputEventAck unhandled_ack(blink::WebInputEvent::MouseWheel,
+                              INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
+  std::unique_ptr<IPC::Message> response1(
+      new InputHostMsg_HandleInputEvent_ACK(0, unhandled_ack));
+  host->OnMessageReceived(*response1);
+
+  // Check that the view delegate got an unhandled wheel event.
+  ASSERT_EQ(YES, view_delegate.get().unhandledWheelEventReceived);
+  view_delegate.get().unhandledWheelEventReceived = NO;
+
+  // Send another wheel event, this time for scrolling by 0 lines (empty event).
+  NSEvent* event2 = MockScrollWheelEventWithPhase(@selector(phaseChanged), 0);
+  [view->cocoa_view() scrollWheel:event2];
+  ASSERT_EQ(1U, process_host->sink().message_count());
+
+  // Indicate that the wheel event was also unhandled.
+  std::unique_ptr<IPC::Message> response2(
+      new InputHostMsg_HandleInputEvent_ACK(0, unhandled_ack));
+  host->OnMessageReceived(*response2);
+
+  // Check that the view delegate ignored the empty unhandled wheel event.
+  ASSERT_EQ(NO, view_delegate.get().unhandledWheelEventReceived);
+
+  // Clean up.
+  host->ShutdownAndDestroyWidget(true);
+}
+
 TEST_F(RenderWidgetHostViewMacTest,
        IgnoreEmptyUnhandledWheelEventWithWheelGestures) {
+  SetupForWheelGestures(true);
+
   // Initialize the view associated with a MockRenderWidgetHostImpl, rather than
   // the MockRenderProcessHost that is set up by the test harness which mocks
   // out |OnMessageReceived()|.
   TestBrowserContext browser_context;
   MockRenderProcessHost* process_host =
       new MockRenderProcessHost(&browser_context);
   process_host->Init();
   MockRenderWidgetHostDelegate delegate;
   int32_t routing_id = process_host->GetNextRoutingID();
   MockRenderWidgetHostImpl* host =
@@ skipping 306 matching lines @@
   // Verify that Event.Latency.OS.MOUSE_WHEEL histogram is computed properly.
   NSEvent* wheelEvent = MockScrollWheelEventWithPhase(@selector(phaseBegan),3);
   [view->cocoa_view() scrollWheel:wheelEvent];
   histogram_tester.ExpectTotalCount("Event.Latency.OS.MOUSE_WHEEL", 1);
 
   // Clean up.
   host->ShutdownAndDestroyWidget(true);
 }
 
 }  // namespace content