[NotLanded] Implement the fetching algorithm of the Web Manifest.

public/web/WebFrameClient.h

Index: public/web/WebFrameClient.h
diff --git a/public/web/WebFrameClient.h b/public/web/WebFrameClient.h
index a9ac9fb262b35a98cc928b2a1e5829eddc8fc46a..15e8bcd93679a320b3151998203b9a2ea56b16d2 100644
--- a/public/web/WebFrameClient.h
+++ b/public/web/WebFrameClient.h
@@ -45,6 +45,8 @@
 #include "public/platform/WebCommon.h"
 #include "public/platform/WebFileSystem.h"
 #include "public/platform/WebFileSystemType.h"
+#include "public/platform/WebManifest.h"
+#include "public/platform/WebManifestError.h"
 #include "public/platform/WebStorageQuotaCallbacks.h"
 #include "public/platform/WebStorageQuotaType.h"
 #include "public/platform/WebURLError.h"
@@ -290,11 +292,20 @@ public:
     // WARNING: This method may be called very frequently.
     virtual void didUpdateCurrentHistoryItem(WebLocalFrame*) { }
 
+    // The frame's theme color has changed.
+    virtual void didChangeThemeColor() { }
+
+
+    // Web Manifest ---------------------------------------------------------
+
     // The frame's manifest has changed.
     virtual void didChangeManifest(WebLocalFrame*) { }
 
-    // The frame's theme color has changed.
-    virtual void didChangeThemeColor() { }
+    // The frame's manifest has been loaded successfully.
+    virtual void didLoadManifest(WebLocalFrame*, WebManifest) { }
+
+    // The frame's manifest loading has failed.
+    virtual void didFailLoadManifest(WebLocalFrame*, WebManifestError) { }
 
 
     // Transition navigations -----------------------------------------------