Invalidate touchEventTargetRects in ScrollingCoordinator when toggling touch emulation.

third_party/WebKit/Source/web/DevToolsEmulator.cpp

Index: third_party/WebKit/Source/web/DevToolsEmulator.cpp
diff --git a/third_party/WebKit/Source/web/DevToolsEmulator.cpp b/third_party/WebKit/Source/web/DevToolsEmulator.cpp
index f87f2e7aca8c984765512bddb16f8cd47627b737..8e46ad489fc8de44be9dfce0d3a7c9f51fdfa207 100644
--- a/third_party/WebKit/Source/web/DevToolsEmulator.cpp
+++ b/third_party/WebKit/Source/web/DevToolsEmulator.cpp
@@ -8,6 +8,7 @@
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/page/Page.h"
+#include "core/page/scrolling/ScrollingCoordinator.h"
 #include "core/style/ComputedStyle.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "public/platform/WebLayerTreeView.h"
@@ -335,6 +336,12 @@ void DevToolsEmulator::setTouchEventEmulationEnabled(bool enabled)
         m_webViewImpl->page()->settings().setMaxTouchPoints(enabled ? 1 : m_originalMaxTouchPoints);
     }
     m_touchEventEmulationEnabled = enabled;
+    if (ScrollingCoordinator* scrollingCoordinator = m_webViewImpl->page()->scrollingCoordinator()) {
+        // We only have to invalidate touch event target rects below, while using big hammer notifyGeometryChanged.
+        // But touch is not toggled often, and so it's fine to do more work vs introducing more fine-grained methods.
+        scrollingCoordinator->notifyGeometryChanged();
+        scrollingCoordinator->updateAfterCompositingChangeIfNeeded();
+    }
     // TODO(dgozman): mainFrameImpl() check in this class should be unnecessary.
     // It is only needed when we reattach and restore InspectorEmulationAgent,
     // which happens before everything has been setup correctly, and therefore