Ignore gesture events in TestPlugin.

With scroll unification, blink::WebPlugin no longer receives gesture
scroll events, which breaks some tests that expect it to see them.
However the only current users of WebPlugin, besides tests, are:

- PDF viewer, which does its own gesture detection and drives scrolling
  from outside the plugin through special hooks.

- Pepper API (still used for NaCL in extensions and Chrome Apps). Pepper
  forwards some inputs, but PepperPluginInstanceImpl::HandleInputEvent
  will drop gesture events as ClassifyInputEvent() would return 0.

- Placeholders that tell the user a plugin couldn't be loaded. These
  aren't scrollable (plugin_placeholders.css sets overflow:hidden).

Therefore, it appears WebPlugin doesn't need to receive gesture events.
Update the test expectations accordingly.

Bug: 1252915
Change-Id: Ib0498479d90bf8368156e68953fcf5fb9ae98951
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3417691
Reviewed-by: David Bokan <bokan@chromium.org>
Reviewed-by: danakj chromium <danakj@chromium.org>
Commit-Queue: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#964589}

content/web_test/renderer/test_plugin.cc

@@ -574,6 +574,12 @@ blink::WebInputEventResult TestPlugin::HandleInputEvent(
     const blink::WebCoalescedInputEvent& coalesced_event,
     ui::Cursor* cursor) {
   const blink::WebInputEvent& event = coalesced_event.Event();
+
+  // Don't log gesture events, which aren't exposed to the Pepper API (see
+  // ClassifyInputEvent in content/renderer/pepper/event_conversion.cc).
+  if (blink::WebInputEvent::IsGestureEventType(event.GetType()))
+    return blink::WebInputEventResult::kNotHandled;
+
   const char* event_name = blink::WebInputEvent::GetName(event.GetType());
   if (!strcmp(event_name, "") || !strcmp(event_name, "Undefined"))
     event_name = "unknown";

third_party/blink/web_tests/plugins/gesture-events-expected.txt

@@ -1,14 +1,7 @@
-Plugin received event: GestureTapDown
-Plugin received event: GestureShowPress
-Plugin received event: GestureTap
 Plugin received event: MouseEnter
 Plugin received event: MouseMove
 Plugin received event: MouseDown
 Plugin received event: MouseUp
-Plugin received event: GestureTapDown
-Plugin received event: GestureScrollBegin
-Plugin received event: GestureScrollUpdate
-Plugin received event: GestureScrollEnd
 PASS successfullyParsed is true
 
 TEST COMPLETE

third_party/blink/web_tests/plugins/gesture-events-scrolled-expected.txt

@@ -1,14 +1,7 @@
-Plugin received event: GestureTapDown
-Plugin received event: GestureShowPress
-Plugin received event: GestureTap
 Plugin received event: MouseEnter
 Plugin received event: MouseMove
 Plugin received event: MouseDown
 Plugin received event: MouseUp
-Plugin received event: GestureTapDown
-Plugin received event: GestureScrollBegin
-Plugin received event: GestureScrollUpdate
-Plugin received event: GestureScrollEnd
 PASS successfullyParsed is true
 
 TEST COMPLETE

third_party/blink/web_tests/plugins/transformed-events-expected.txt

@@ -18,22 +18,10 @@ Plugin received event: MouseMove
 * 10.00, 10.00
 Plugin received event: MouseWheel
 * 10.00, 10.00
-Plugin received event: GestureScrollBegin
-* 10.00, 10.00
-Plugin received event: GestureScrollUpdate
-* 10.00, 10.00
-Plugin received event: GestureScrollEnd
-* 10.00, 10.00
 Plugin received event: TouchStart
 * 10.00, 10.00: Pressed
-Plugin received event: GestureTapDown
-* 10.00, 10.00
 Plugin received event: TouchEnd
 * 10.00, 10.00: Released
-Plugin received event: GestureShowPress
-* 10.00, 10.00
-Plugin received event: GestureTap
-* 10.00, 10.00
 Plugin received event: MouseMove
 * 10.00, 10.00
 Plugin received event: MouseDown