PlzNavigate: cancel any scheduled navigations when deciding to let the embedder handle a navigation.

third_party/WebKit/Source/core/loader/FrameLoader.cpp

Index: third_party/WebKit/Source/core/loader/FrameLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameLoader.cpp b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
index 68831e29a0776cb5956f332bd655788707103e60..1f3658cab701eebe0699a55bc6da19fad8cdb34a 100644
--- a/third_party/WebKit/Source/core/loader/FrameLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
@@ -1635,6 +1635,8 @@ bool FrameLoader::shouldContinueForNavigationPolicy(
     // Mark the frame as loading since the embedder is handling the navigation.
     m_progressTracker->progressStarted();
 
+    m_frame->navigationScheduler().cancel();
+
     // If this is a form submit, dispatch that a form is being submitted
     // since the embedder is handling the navigation.
     if (form)