Handle slow path case kHitTestAsk in HitTestQuery.

1. If the target hit-test region we find in HitTestQuery has kHitTestAsk
flag set, we need to fall back to the slow path - ask renderer to do the
targeting. Return the viz::Target we find with kHitTestAsk in that case.

2. In RenderWidgetHostInputEventRouter::FindViewAtLocation, set
RenderWidgetTargetResult::should_query_view to be true if kHitTestAsk is
set in the target we received.

Bug: 803548
Test: viz_unittests
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I7df66f2e09a15308ee02ee4918ab1f43077b1fbd
Reviewed-on: https://chromium-review.googlesource.com/876997Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Commit-Queue: Ria Jiang <riajiang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531060}

components/viz/host/hit_test/hit_test_query.cc

@@ -121,16 +121,12 @@ bool HitTestQuery::FindTargetInRegionForLocation(
           : (region->flags & mojom::kHitTestMouse) != 0u;
   if (!match_touch_or_mouse_region)
     return false;
-  if (region->flags & mojom::kHitTestMine) {
+  if (region->flags & (mojom::kHitTestMine | mojom::kHitTestAsk)) {
     target->frame_sink_id = region->frame_sink_id;
     target->location_in_target = location_in_target;
     target->flags = region->flags;
     return true;
   }
-  if (region->flags & mojom::kHitTestAsk) {
-    target->flags = region->flags;
-    return true;
-  }
   return false;
 }
 

components/viz/host/hit_test/hit_test_query_unittest.cc

@@ -928,8 +928,8 @@ TEST_F(HitTestQueryTest, RootHitTestAskFlag) {
   // point1 is inside e but we have to ask clients for targeting.
   Target target1 =
       hit_test_query().FindTargetForLocation(EventSource::MOUSE, point1);
-  EXPECT_EQ(target1.frame_sink_id, FrameSinkId());
-  EXPECT_EQ(target1.location_in_target, gfx::Point());
+  EXPECT_EQ(target1.frame_sink_id, e_id);
+  EXPECT_EQ(target1.location_in_target, point1);
   EXPECT_EQ(target1.flags, mojom::kHitTestAsk | mojom::kHitTestMouse);
 
   // point2 is on the bounds of e so no target found.
@@ -992,8 +992,8 @@ TEST_F(HitTestQueryTest, ChildHitTestAskFlag) {
   // shouldn't go back to e.
   Target target3 =
       hit_test_query().FindTargetForLocation(EventSource::MOUSE, point3);
-  EXPECT_EQ(target3.frame_sink_id, FrameSinkId());
-  EXPECT_EQ(target3.location_in_target, gfx::Point());
+  EXPECT_EQ(target3.frame_sink_id, c2_id);
+  EXPECT_EQ(target3.location_in_target, gfx::Point(100, 100));
   EXPECT_EQ(target3.flags, mojom::kHitTestAsk | mojom::kHitTestMouse);
 }
 

content/browser/renderer_host/render_widget_host_input_event_router.cc

@@ -19,6 +19,7 @@
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/browser/renderer_host/render_widget_host_view_child_frame.h"
 #include "content/common/frame_messages.h"
+#include "services/viz/public/interfaces/hit_test/hit_test_region_list.mojom.h"
 #include "third_party/WebKit/public/platform/WebInputEvent.h"
 
 namespace {
@@ -308,6 +309,8 @@ RenderWidgetTargetResult RenderWidgetHostInputEventRouter::FindViewAtLocation(
     } else {
       *transformed_point = point;
     }
+    if (target.flags & viz::mojom::kHitTestAsk)
+      query_renderer = true;
   } else {
     // Short circuit if owner_map has only one RenderWidgetHostView, no need for
     // hit testing.