Add WebPrescientNetworking to trigger preconnect from Blink.

Source/Platform/chromium/public/WebPrescientNetworking.h

Index: Source/Platform/chromium/public/WebPrescientNetworking.h
diff --git a/Source/Platform/chromium/public/WebGraphicsContext3DProvider.h b/Source/Platform/chromium/public/WebPrescientNetworking.h
similarity index 64%
copy from Source/Platform/chromium/public/WebGraphicsContext3DProvider.h
copy to Source/Platform/chromium/public/WebPrescientNetworking.h
index dba2216773526377c53b27a9d6830bce0c25fc48..27fceea01da4f5c022f2f7b2d303ae3931897999 100644
--- a/Source/Platform/chromium/public/WebGraphicsContext3DProvider.h
+++ b/Source/Platform/chromium/public/WebPrescientNetworking.h
@@ -28,24 +28,35 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef WebGraphicsContext3DProvider_h
-#define WebGraphicsContext3DProvider_h
+#ifndef WebPrescientNetworking_h
+#define WebPrescientNetworking_h
 
 #include "WebCommon.h"
 
-class GrContext;
-
 namespace WebKit {
-class WebGraphicsContext3D;
 
-class WebGraphicsContext3DProvider {
+class WebURL;
+
+// FIXME: Passing preconnect motivation to the platform is layering vioration.
+// However, this is done temporarily to perform a Finch field trial to enable
+// preconnect in different triggers one at a time. This enum can be safely
+// removed after the field trial is done.
+enum WebPreconnectMotivation {
+    WebPreconnectMotivationLinkMouseDown,
+    WebPreconnectMotivationLinkMouseOver,
+    WebPreconnectMotivationLinkTapUnconfirmed,
+    WebPreconnectMotivationLinkTapDown,
+};
+
+class WebPrescientNetworking {
 public:
-    virtual ~WebGraphicsContext3DProvider() { }
+    virtual ~WebPrescientNetworking() { }
 
-    virtual WebGraphicsContext3D* context3d() = 0;
-    virtual GrContext* grContext() = 0;
+    // When a page navigation is speculated, preconnect is triggered to hide
+    // session initialization latency to the server providing the page resource.
+    virtual void preconnect(const WebURL&, WebPreconnectMotivation) { }
 };
 
 } // namespace WebKit
 
-#endif
+#endif // WebPrescientNetworking_h