Add logic to resolve permission mismatches in Android M for webrtc.

chrome/browser/permissions/permission_update_infobar_delegate_android.cc

 // Copyright 2015 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/permissions/permission_update_infobar_delegate_android.h"
 
 #include <string>
 
 #include "base/android/jni_array.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 58 matching lines @@
 }
 
 // static
 bool PermissionUpdateInfoBarDelegate::RegisterPermissionUpdateInfoBarDelegate(
     JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 void PermissionUpdateInfoBarDelegate::OnPermissionResult(
     JNIEnv* env, jobject obj, jboolean all_permissions_granted) {
-  callback_.Run(all_permissions_granted);
+  PermissionUpdatedCallback cb = callback_;

[Guido Urdaneta, 2015/09/23 13:32:14]

Can you use base::ResetAndReturn() here?

[Ted C, 2015/09/23 19:45:34]

Neat!  Done

[Peter Kasting, 2016/09/21 21:33:44]

This change got referenced in another review I was doing for some Android
infobar code.

Why is it important to save off the callback before calling it (i.e. using
ResetAndReturn() instead of just a direct Run())?  This is subtle, and

(1) Other people are copying this without it being clear to me that they need
it, and
(2) I'm not sure how to _be_ clear about when it's needed

Understanding why you were doing this would help me.

[Peter Kasting, 2016/09/21 21:37:08]

To be clear: I understand why you want to reset the callback, so it doesn't run
in the destructor.  What I _don't_ understand is why the order needs to be
"reset first, then run" instead of just:

  callback_.Run();
  callback_.Reset();

Can |callback_| destroy |this|?  But if it could, then the RemoveSelf() call
wouldn't be safe either.  So I don't understand why the hoop-jumping.

+  callback_.Reset();
+  cb.Run(all_permissions_granted);
+
   infobar()->RemoveSelf();
 }
 
 PermissionUpdateInfoBarDelegate::PermissionUpdateInfoBarDelegate(
     content::WebContents* web_contents,
     const std::vector<ContentSettingsType>& content_settings_types,
     const PermissionUpdatedCallback& callback)
     : ConfirmInfoBarDelegate(),
       content_settings_types_(content_settings_types),
       callback_(callback) {
   std::vector<int> content_settings_type_values;
   for (ContentSettingsType type : content_settings_types)
     content_settings_type_values.push_back(type);
 
   JNIEnv* env = base::android::AttachCurrentThread();
   java_delegate_.Reset(Java_PermissionUpdateInfoBarDelegate_create(
       env,
       reinterpret_cast<intptr_t>(this),
       web_contents->GetJavaWebContents().obj(),
       base::android::ToJavaIntArray(env, content_settings_type_values).obj()));
 
   content::ContentViewCore* cvc =
         content::ContentViewCore::FromWebContents(web_contents);
   window_android_ = cvc->GetWindowAndroid();
 }
 
 PermissionUpdateInfoBarDelegate::~PermissionUpdateInfoBarDelegate() {
   Java_PermissionUpdateInfoBarDelegate_onNativeDestroyed(
       base::android::AttachCurrentThread(), java_delegate_.obj());
+
+  if (!callback_.is_null())
+    callback_.Run(false);
 }
 
 int PermissionUpdateInfoBarDelegate::GetIconId() const {
   return IDR_INFOBAR_WARNING;
 }
 
 base::string16 PermissionUpdateInfoBarDelegate::GetMessageText() const {
   int missing_permission_count = 0;
   int message_id = IDS_INFOBAR_MISSING_MULTIPLE_PERMISSIONS_TEXT;
 
@@ skipping 41 matching lines @@
   return l10n_util::GetStringUTF16(IDS_INFOBAR_UPDATE_PERMISSIONS_BUTTON_TEXT);
 }
 
 bool PermissionUpdateInfoBarDelegate::Accept() {
   Java_PermissionUpdateInfoBarDelegate_requestPermissions(
       base::android::AttachCurrentThread(), java_delegate_.obj());
   return false;
 }
 
 bool PermissionUpdateInfoBarDelegate::Cancel() {
-  callback_.Run(false);
+  PermissionUpdatedCallback cb = callback_;

[Guido Urdaneta, 2015/09/23 13:32:14]

base::ResetAndReturn()

+  callback_.Reset();
+  cb.Run(false);
+
   return true;
 }
+
+void PermissionUpdateInfoBarDelegate::InfoBarDismissed() {
+  PermissionUpdatedCallback cb = callback_;
+  callback_.Reset();
+  cb.Run(false);
+}