Reset Frame::m_hasReceivedUserGesture for main frames on navigation

Child frames have some degree of continuity across navigations: the
contents are still embedded in the same document. Let them continue to
propagate user gesture state across navigations. However, main frames
don't have that continuity and should reset their user gesture state
on navigation.

TEST=DocumentUserGestureTokenTest.Navigate
BUG=chromedriver:922

Review-Url: https://codereview.chromium.org/2721423003
Cr-Commit-Position: refs/heads/master@{#456134}

third_party/WebKit/Source/core/dom/DocumentUserGestureTokenTest.cpp

@@ -43,4 +43,14 @@ TEST_F(DocumentUserGestureTokenTest, NewGesture) {
   EXPECT_TRUE(document().frame()->hasReceivedUserGesture());
 }
 
+TEST_F(DocumentUserGestureTokenTest, Navigate) {
+  DocumentUserGestureToken::create(&document());
+  ASSERT_TRUE(document().frame()->hasReceivedUserGesture());
+
+  // Navigate to a different Document. In the main frame, user gesture state
+  // will get reset.
+  document().frame()->loader().load(FrameLoadRequest(nullptr, KURL()));
+  EXPECT_FALSE(document().frame()->hasReceivedUserGesture());
+}
+
 }  // namespace blink

third_party/WebKit/Source/core/frame/LocalFrame.cpp

@@ -515,6 +515,8 @@ void LocalFrame::documentAttached() {
   selection().documentAttached(document());
   inputMethodController().documentAttached(document());
   spellChecker().documentAttached(document());
+  if (isMainFrame())
+    m_hasReceivedUserGesture = false;
 }
 
 LocalDOMWindow* LocalFrame::domWindow() const {

third_party/WebKit/Source/web/WebFrame.cpp

@@ -110,7 +110,7 @@ bool WebFrame::swap(WebFrame* frame) {
                                                      uniqueName);
   }
 
-  if (oldFrame->hasReceivedUserGesture())
+  if (m_parent && oldFrame->hasReceivedUserGesture())
     frame->toImplBase()->frame()->setDocumentHasReceivedUserGesture();
 
   frame->toImplBase()->frame()->getWindowProxyManager()->setGlobals(globals);