Public Sessions - prompt the user for pageCapture requests

chrome/browser/extensions/api/page_capture/page_capture_api.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/api/page_capture/page_capture_api.h"
 
 #include <limits>
 #include <memory>
 
 #include "base/bind.h"
+#include "base/bind_helpers.h"
 #include "base/files/file_util.h"
+#include "base/memory/ptr_util.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/extensions/extension_tab_util.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/profiles/profiles_state.h"
 #include "content/public/browser/child_process_security_policy.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/mhtml_generation_params.h"
 #include "extensions/common/extension_messages.h"
 
+#if defined (OS_CHROMEOS)
+#include "chrome/browser/chromeos/extensions/public_session_permission_helper.h"
+#endif
+
 using content::BrowserThread;
 using content::ChildProcessSecurityPolicy;
 using content::WebContents;
 using extensions::PageCaptureSaveAsMHTMLFunction;
 using storage::ShareableFileReference;
 
 namespace SaveAsMHTML = extensions::api::page_capture::SaveAsMHTML;
 
 namespace {
 
 const char kFileTooBigError[] = "The MHTML file generated is too big.";
 const char kMHTMLGenerationFailedError[] = "Failed to generate MHTML.";
 const char kTemporaryFileError[] = "Failed to create a temporary file.";
 const char kTabClosedError[] = "Cannot find the tab for this request.";
+#if defined(OS_CHROMEOS)
+const char kUserDenied[] = "User denied request.";
+#endif
 
 }  // namespace
 
 static PageCaptureSaveAsMHTMLFunction::TestDelegate* test_delegate_ = NULL;
 
 PageCaptureSaveAsMHTMLFunction::PageCaptureSaveAsMHTMLFunction() {
 }
 
 PageCaptureSaveAsMHTMLFunction::~PageCaptureSaveAsMHTMLFunction() {
   if (mhtml_file_.get()) {
     storage::ShareableFileReference* to_release = mhtml_file_.get();
     to_release->AddRef();
     mhtml_file_ = NULL;
     BrowserThread::ReleaseSoon(BrowserThread::IO, FROM_HERE, to_release);
   }
 }
 
 void PageCaptureSaveAsMHTMLFunction::SetTestDelegate(TestDelegate* delegate) {
   test_delegate_ = delegate;
 }
 
 bool PageCaptureSaveAsMHTMLFunction::RunAsync() {
   params_ = SaveAsMHTML::Params::Create(*args_);
   EXTENSION_FUNCTION_VALIDATE(params_.get());
 
   AddRef();  // Balanced in ReturnFailure/ReturnSuccess()
 
+  // In Public Sessions, extensions (and apps) are force-installed by admin
+  // policy so the user does not get a chance to review the permissions for
+  // these extensions. This is not acceptable from a security/privacy
+  // standpoint, so when an extension uses the PageCapture API for the first
+  // time, we show the user a dialog where they can choose whether to allow the
+  // extension access to the API.
+#if defined(OS_CHROMEOS)
+  if (profiles::IsPublicSession()) {
+    WebContents* web_contents = GetWebContents();
+    if (!web_contents) {
+      ReturnFailure(kTabClosedError);
+      return true;
+    }
+    auto success_callback = base::Bind(
+        base::IgnoreResult(&BrowserThread::PostTask), BrowserThread::FILE,
+        FROM_HERE,
+        base::Bind(&PageCaptureSaveAsMHTMLFunction::CreateTemporaryFile,
+                   base::Unretained(this)));

[Devlin, 2017/01/30 17:04:17]

explain why the unretained()s are safe.

Alternatively, ExtensionFunctions are ref-counted, so you could just pass |this|
directly.

[Ivan Šandrk, 2017/01/30 18:14:20]

Done.

+    auto failure_callback =
+        base::Bind(&PageCaptureSaveAsMHTMLFunction::ReturnFailure,
+                   base::Unretained(this), kUserDenied);
+    extensions::PublicSessionPermissionHelper::HandlePermissionRequest(
+        *extension(), {APIPermission::kPageCapture}, web_contents,
+        success_callback, failure_callback);
+    return true;
+  }
+#endif
+
   BrowserThread::PostTask(
       BrowserThread::FILE, FROM_HERE,
       base::Bind(&PageCaptureSaveAsMHTMLFunction::CreateTemporaryFile, this));
   return true;
 }
 
 bool PageCaptureSaveAsMHTMLFunction::OnMessageReceived(
     const IPC::Message& message) {
   if (message.type() != ExtensionHostMsg_ResponseAck::ID)
     return false;
@@ skipping 117 matching lines @@
                                     GetProfile(),
                                     include_incognito(),
                                     &browser,
                                     NULL,
                                     &web_contents,
                                     NULL)) {
     return NULL;
   }
   return web_contents;
 }