Reject connection attempts without prompt if target app doesn't handle the event anyway.

If a connection is not going to succeed, the user shouldn't be prompted to allow it.

BUG=442497

Review URL: https://codereview.chromium.org/800853006

Cr-Commit-Position: refs/heads/master@{#309569}

chrome/browser/extensions/api/messaging/message_service.cc

@@ -30,6 +30,7 @@
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/browser/web_contents.h"
+#include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_host.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
@@ -343,8 +344,25 @@ void MessageService::OpenChannelToExtension(
     //   enabling in incognito. In practice this means platform apps only.
     if (!is_web_connection || IncognitoInfo::IsSplitMode(target_extension) ||
         target_extension->can_be_incognito_enabled()) {
-      DispatchOnDisconnect(source, receiver_port_id,
-                           kReceivingEndDoesntExistError);
+      OnOpenChannelAllowed(params.Pass(), false);
+      return;
+    }
+
+    // If the target extension isn't even listening for connect/message events,
+    // there is no need to go any further and the connection should be
+    // rejected without showing a prompt. See http://crbug.com/442497
+    EventRouter* event_router = EventRouter::Get(context);
+    const char* const events[] = {"runtime.onConnectExternal",
+                                  "runtime.onMessageExternal",
+                                  "extension.onRequestExternal",
+                                  nullptr};
+    bool has_event_listener = false;
+    for (const char* const* event = events; *event; event++) {
+      has_event_listener |=
+          event_router->ExtensionHasEventListener(target_extension_id, *event);
+    }
+    if (!has_event_listener) {
+      OnOpenChannelAllowed(params.Pass(), false);
       return;
     }
 

chrome/browser/extensions/extension_messages_apitest.cc

@@ -306,7 +306,8 @@ class ExternallyConnectableMessagingTest : public ExtensionApiTest {
     return extension;
   }
 
-  scoped_refptr<const Extension> LoadChromiumConnectableApp() {
+  scoped_refptr<const Extension> LoadChromiumConnectableApp(
+      bool with_event_handlers = true) {
     scoped_refptr<const Extension> extension =
         LoadExtensionIntoDir(&web_connectable_dir_,
                              "{"
@@ -321,7 +322,8 @@ class ExternallyConnectableMessagingTest : public ExtensionApiTest {
                              "  \"manifest_version\": 2,"
                              "  \"name\": \"app_connectable\","
                              "  \"version\": \"1.0\""
-                             "}");
+                             "}",
+                             with_event_handlers);
     CHECK(extension.get());
     return extension;
   }
@@ -382,26 +384,33 @@ class ExternallyConnectableMessagingTest : public ExtensionApiTest {
  private:
   scoped_refptr<const Extension> LoadExtensionIntoDir(
       TestExtensionDir* dir,
-      const std::string& manifest) {
+      const std::string& manifest,
+      bool with_event_handlers = true) {
     dir->WriteManifest(manifest);
-    dir->WriteFile(FILE_PATH_LITERAL("background.js"),
-                   base::StringPrintf(
-        "function maybeClose(message) {\n"
-        "  if (message.indexOf('%s') >= 0)\n"
-        "    window.setTimeout(function() { window.close() }, 0);\n"
-        "}\n"
-        "chrome.runtime.onMessageExternal.addListener(\n"
-        "    function(message, sender, reply) {\n"
-        "  reply({ message: message, sender: sender });\n"
-        "  maybeClose(message);\n"
-        "});\n"
-        "chrome.runtime.onConnectExternal.addListener(function(port) {\n"
-        "  port.onMessage.addListener(function(message) {\n"
-        "    port.postMessage({ message: message, sender: port.sender });\n"
-        "    maybeClose(message);\n"
-        "  });\n"
-        "});\n",
-                   close_background_message()));
+    if (with_event_handlers) {
+      dir->WriteFile(
+          FILE_PATH_LITERAL("background.js"),
+          base::StringPrintf(
+              "function maybeClose(message) {\n"
+              "  if (message.indexOf('%s') >= 0)\n"
+              "    window.setTimeout(function() { window.close() }, 0);\n"
+              "}\n"
+              "chrome.runtime.onMessageExternal.addListener(\n"
+              "    function(message, sender, reply) {\n"
+              "  reply({ message: message, sender: sender });\n"
+              "  maybeClose(message);\n"
+              "});\n"
+              "chrome.runtime.onConnectExternal.addListener(function(port) {\n"
+              "  port.onMessage.addListener(function(message) {\n"
+              "    port.postMessage({ message: message, sender: port.sender "
+              "});\n"
+              "    maybeClose(message);\n"
+              "  });\n"
+              "});\n",
+              close_background_message()));
+    } else {
+      dir->WriteFile(FILE_PATH_LITERAL("background.js"), "");
+    }
     return LoadExtension(dir->unpacked_path());
   }
 
@@ -735,6 +744,36 @@ IN_PROC_BROWSER_TEST_F(ExternallyConnectableMessagingTest,
       CanConnectAndSendMessagesToFrame(incognito_frame, extension.get(), NULL));
 }
 
+// Tests connection from incognito tabs when the extension doesn't have an event
+// handler for the connection event.
+IN_PROC_BROWSER_TEST_F(ExternallyConnectableMessagingTest,
+                       FromIncognitoNoEventHandlerInApp) {
+  InitializeTestServer();
+
+  scoped_refptr<const Extension> app = LoadChromiumConnectableApp(false);
+  ASSERT_TRUE(app->is_platform_app());
+
+  Browser* incognito_browser = ui_test_utils::OpenURLOffTheRecord(
+      profile()->GetOffTheRecordProfile(), chromium_org_url());
+  content::RenderFrameHost* incognito_frame =
+      incognito_browser->tab_strip_model()
+          ->GetActiveWebContents()
+          ->GetMainFrame();
+
+  {
+    IncognitoConnectability::ScopedAlertTracker alert_tracker(
+        IncognitoConnectability::ScopedAlertTracker::ALWAYS_ALLOW);
+
+    // No connection because incognito-enabled hasn't been set for the app, and
+    // the app hasn't installed event handlers.
+    EXPECT_EQ(
+        COULD_NOT_ESTABLISH_CONNECTION_ERROR,
+        CanConnectAndSendMessagesToFrame(incognito_frame, app.get(), NULL));
+    // No dialog should have been shown.
+    EXPECT_EQ(0, alert_tracker.GetAndResetAlertCount());
+  }
+}
+
 // Tests connection from incognito tabs when the user accepts the connection
 // request. Spanning mode only. Separate tests for apps and extensions.
 //

chrome/common/extensions/api/extension.json

@@ -203,9 +203,6 @@
         "name": "onRequestExternal",
         "deprecated": "Please use $(ref:runtime.onMessageExternal).",
         "type": "function",
-        "options": {
-          "unmanaged": true
-        },
         "description": "Fired when a request is sent from another extension.",
         "parameters": [
           {"name": "request", "type": "any", "optional": true, "description": "The request sent by the calling script."},

extensions/common/api/runtime.json

@@ -424,9 +424,6 @@
         "name": "onConnectExternal",
         "type": "function",
         "nocompile": true,
-        "options": {
-          "unmanaged": true
-        },
         "description": "Fired when a connection is made from another extension.",
         "parameters": [
           {"$ref": "Port", "name": "port"}
@@ -435,10 +432,10 @@
       {
         "name": "onMessage",
         "type": "function",
+        "nocompile": true,
         "options": {
           "unmanaged": true
         },
-        "nocompile": true,
         "description": "Fired when a message is sent from either an extension process or a content script.",
         "parameters": [
           {"name": "message", "type": "any", "optional": true, "description": "The message sent by the calling script."},
@@ -454,9 +451,6 @@
       {
         "name": "onMessageExternal",
         "type": "function",
-        "options": {
-          "unmanaged": true
-        },
         "nocompile": true,
         "description": "Fired when a message is sent from another extension/app. Cannot be used in a content script.",
         "parameters": [