Change beforeinstallprompt event to take an array of platforms.

Source/modules/app_banner/AppBannerController.cpp

Index: Source/modules/app_banner/AppBannerController.cpp
diff --git a/Source/modules/app_banner/AppBannerController.cpp b/Source/modules/app_banner/AppBannerController.cpp
index 52324957fbe6da20b8291c1075914d5532f5d58d..02417723cd9fd69dfaccee1f863feb7ce1c712e4 100644
--- a/Source/modules/app_banner/AppBannerController.cpp
+++ b/Source/modules/app_banner/AppBannerController.cpp
@@ -10,18 +10,22 @@
 #include "core/frame/LocalFrame.h"
 #include "modules/app_banner/BeforeInstallPromptEvent.h"
 #include "platform/RuntimeEnabledFeatures.h"
+#include "public/platform/WebVector.h"
 #include "public/platform/modules/app_banner/WebAppBannerPromptReply.h"
 
 namespace blink {
 
 // static
-void AppBannerController::willShowInstallBannerPrompt(LocalFrame* frame, const WebString& platform, WebAppBannerPromptReply* reply)
+void AppBannerController::willShowInstallBannerPrompt(LocalFrame* frame, const WebVector<WebString>& platforms, WebAppBannerPromptReply* reply)
 {
     ASSERT(RuntimeEnabledFeatures::appBannerEnabled());
 
+    Vector<String> wtfPlatforms;
+    for (const WebString& platform : platforms)
+        wtfPlatforms.append(platform);
     // dispatchEvent() returns whether the default behavior can happen. In other
     // words, it returns false if preventDefault() was called.
-    *reply = frame->domWindow()->dispatchEvent(BeforeInstallPromptEvent::create(EventTypeNames::beforeinstallprompt, platform))
+    *reply = frame->domWindow()->dispatchEvent(BeforeInstallPromptEvent::create(EventTypeNames::beforeinstallprompt, wtfPlatforms))
         ? WebAppBannerPromptReply::None : WebAppBannerPromptReply::Cancel;
 }