Speculatively launch Service Workers on mouse/touch events. [1/5]

third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp b/third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp
index e74548006ea6219402dacb1a555a086e67eb9440..8ced595746198909fe6f53676e91fd6f3c575bbd 100644
--- a/third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp
@@ -35,13 +35,84 @@
 #include "core/loader/FrameLoaderClient.h"
 #include "core/loader/PingLoader.h"
 #include "core/page/ChromeClient.h"
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/network/NetworkHints.h"
 #include "platform/weborigin/SecurityPolicy.h"
+#include "public/platform/WebNavigationHintType.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
+class HTMLAnchorElement::NavigationHintSender : public GarbageCollected<HTMLAnchorElement::NavigationHintSender> {
+public:
+    static NavigationHintSender* create(HTMLAnchorElement* anchorElement)
+    {
+        return new NavigationHintSender(anchorElement);
+    }
+    void handleEvent(Event*);
+
+    DECLARE_VIRTUAL_TRACE();
+
+private:
+    explicit NavigationHintSender(HTMLAnchorElement*);
+    bool shouldSendNavigationHint() const;
+    void maybeSendNavigationHint(WebNavigationHintType);
+
+    Member<HTMLAnchorElement> m_anchorElement;
+};
+
+void HTMLAnchorElement::NavigationHintSender::handleEvent(Event* event)
+{
+    if (event->type() == EventTypeNames::mousedown && event->isMouseEvent() && toMouseEvent(event)->button() == LeftButton)
+        maybeSendNavigationHint(WebNavigationHintType::LinkMouseDown);
+    else if (event->type() == EventTypeNames::gesturetapunconfirmed)
+        maybeSendNavigationHint(WebNavigationHintType::LinkTapUnconfirmed);
+    else if (event->type() == EventTypeNames::gestureshowpress)
+        maybeSendNavigationHint(WebNavigationHintType::LinkTapDown);
+}
+
+DEFINE_TRACE(HTMLAnchorElement::NavigationHintSender)
+{
+    visitor->trace(m_anchorElement);
+}
+
+HTMLAnchorElement::NavigationHintSender::NavigationHintSender(HTMLAnchorElement* anchorElement)
+    : m_anchorElement(anchorElement)
+{
+}
+
+bool HTMLAnchorElement::NavigationHintSender::shouldSendNavigationHint() const
+{
+    const KURL& url = m_anchorElement->href();
+    if (!url.protocolIsInHTTPFamily())

[falken, 2016/06/09 13:24:16]

Why is it restricted to HTTP? Is this because the NavigationHint is for service
worker? If so, maybe this function should be named
shouldSendNavigationHintForServiceWorker and we could add a comment about how SW
is restricted to http?

Also technically we should use
SchemeRegistry::shouldTreatURLSchemeAsAllowingServiceWorkers instead. (But
that's a bit annoying because it uses a mutex)

[horo, 2016/06/14 11:03:14]

Done.

+        return false;
+    Document& document = m_anchorElement->document();
+    if (!document.frame())
+        return false;
+    if (!document.getSecurityOrigin()->canDisplay(url))
+        return false;
+    if (url.hasFragmentIdentifier() && equalIgnoringFragmentIdentifier(document.url(), url))

[falken, 2016/06/09 13:24:16]

Is this avoiding the hint if the link is to current document? Why is that
needed?

Does hasFragmentIdentifier need to be called? 

[horo, 2016/06/14 11:03:14]

When the user clicks a link which is to the current document with #hash, the
network request is not fetched. So we don't need to start ServiceWorker.
So returns false here.

If #hash is not set, the network request is fetched. So we should start
ServiceWorker.

+        return false;
+
+    // If the opener is to be suppressed and the target frame name is set,
+    // WebContentsImpl::CreateNewWindow() will create a new process when the
+    // user click the anchor element. In such case we shouldn't start the
+    // Service Worker not to keep the current process running.

[falken, 2016/06/09 13:24:16]

Ah yes this code is pretty SW-specific but the naming doesn't give a hint of
that.

+    const bool openerSuppressed = m_anchorElement->hasRel(RelationNoReferrer) || m_anchorElement->hasRel(RelationNoOpener);
+    if (openerSuppressed && !m_anchorElement->getAttribute(targetAttr).isEmpty())
+        return false;
+    return true;
+}
+
+void HTMLAnchorElement::NavigationHintSender::maybeSendNavigationHint(WebNavigationHintType type)
+{
+    if (!shouldSendNavigationHint())
+        return;
+
+    // TODO(horo): Send the navigation hint message to the browser process.
+}
+
 HTMLAnchorElement::HTMLAnchorElement(const QualifiedName& tagName, Document& document)
     : HTMLElement(tagName, document)
     , m_linkRelations(0)
@@ -59,6 +130,12 @@ HTMLAnchorElement::~HTMLAnchorElement()
 {
 }
 
+DEFINE_TRACE(HTMLAnchorElement)
+{
+    visitor->trace(m_navigationHintsender);
+    HTMLElement::trace(visitor);
+}
+
 bool HTMLAnchorElement::supportsFocus() const
 {
     if (hasEditableStyle())
@@ -162,6 +239,10 @@ void HTMLAnchorElement::defaultEventHandler(Event* event)
             return;
         }
 
+        // TODO(horo): Call NavigationHintSender::handleEvent() when
+        // SpeculativeLaunchServiceWorker feature is enabled.
+        // ensureNavigationHintSender()->handleEvent(event);
+
         if (isLinkClick(event) && isLiveLink()) {
             handleClick(event);
             return;
@@ -396,4 +477,11 @@ Node::InsertionNotificationRequest HTMLAnchorElement::insertedInto(ContainerNode
     return request;
 }
 
+HTMLAnchorElement::NavigationHintSender* HTMLAnchorElement::ensureNavigationHintSender()
+{
+    if (!m_navigationHintsender)
+        m_navigationHintsender = NavigationHintSender::create(this);
+    return m_navigationHintsender;
+}
+
 } // namespace blink