Explicitly suppress scrolling for wheel events that will trigger zooming

content/common/input/web_input_event_traits_unittest.cc

Index: content/common/input/web_input_event_traits_unittest.cc
diff --git a/content/common/input/web_input_event_traits_unittest.cc b/content/common/input/web_input_event_traits_unittest.cc
index 7a7cb7ff8b3e878eec275c8445494fbb8a6aefa4..d4bbeba8a70b0dbf949559c86087ac74ee03186a 100644
--- a/content/common/input/web_input_event_traits_unittest.cc
+++ b/content/common/input/web_input_event_traits_unittest.cc
@@ -51,6 +51,17 @@ class WebInputEventTraitsTest : public testing::Test {
     event.y = y;
     return event;
   }
+
+  static WebMouseWheelEvent CreateMouseWheel(float deltaX,
+                                             float deltaY,
+                                             bool canScroll) {
+    WebMouseWheelEvent event;
+    event.type = WebInputEvent::MouseWheel;
+    event.deltaX = deltaX;
+    event.deltaY = deltaY;
+    event.canScroll = canScroll;
+    return event;
+  }
 };
 
 TEST_F(WebInputEventTraitsTest, TouchEventCoalescing) {
@@ -162,6 +173,31 @@ TEST_F(WebInputEventTraitsTest, PinchEventCoalescing) {
   EXPECT_EQ(numeric_limits<float>::max(), pinch1.data.pinchUpdate.scale);
 }
 
+TEST_F(WebInputEventTraitsTest, WebMouseWheelEventCoalescing) {
+  WebMouseWheelEvent mouseWheel0 =
+      CreateMouseWheel(1, 1, true);
+  WebMouseWheelEvent mouseWheel1 =
+      CreateMouseWheel(2, 2, true);
+
+  // WebMouseWheelEvent objects with same values except different deltaX and
+  // deltaY should coalesce.
+  EXPECT_TRUE(WebInputEventTraits::CanCoalesce(mouseWheel0, mouseWheel1));
+
+  mouseWheel0 = CreateMouseWheel(1, 1, true);
+  mouseWheel1 = CreateMouseWheel(1, 1, false);
+
+  // WebMouseWheelEvent objects with different canScroll values should not
+  // coalesce.
+  EXPECT_FALSE(WebInputEventTraits::CanCoalesce(mouseWheel0, mouseWheel1));
+
+  // WebMouseWheelEvent objects with different modifiers should not coalesce.
+  mouseWheel0 = CreateMouseWheel(1, 1, true);
+  mouseWheel1 = CreateMouseWheel(1, 1, true);
+  mouseWheel0.modifiers = blink::WebInputEvent::ControlKey;
+  mouseWheel1.modifiers = blink::WebInputEvent::ShiftKey;
+  EXPECT_FALSE(WebInputEventTraits::CanCoalesce(mouseWheel0, mouseWheel1));
+}
+
 // Very basic smoke test to ensure stringification doesn't explode.
 TEST_F(WebInputEventTraitsTest, ToString) {
   WebKeyboardEvent key;