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

chrome/browser/permissions/permission_update_infobar_delegate_android.cc

Index: chrome/browser/permissions/permission_update_infobar_delegate_android.cc
diff --git a/chrome/browser/permissions/permission_update_infobar_delegate_android.cc b/chrome/browser/permissions/permission_update_infobar_delegate_android.cc
index 35ad88576f527f697753a71afb472fefb1a99b1c..680c48121c42f6ec46e45925a846dba842c05b91 100644
--- a/chrome/browser/permissions/permission_update_infobar_delegate_android.cc
+++ b/chrome/browser/permissions/permission_update_infobar_delegate_android.cc
@@ -76,7 +76,10 @@ bool PermissionUpdateInfoBarDelegate::RegisterPermissionUpdateInfoBarDelegate(
 
 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();
 }
 
@@ -106,6 +109,9 @@ PermissionUpdateInfoBarDelegate::PermissionUpdateInfoBarDelegate(
 PermissionUpdateInfoBarDelegate::~PermissionUpdateInfoBarDelegate() {
   Java_PermissionUpdateInfoBarDelegate_onNativeDestroyed(
       base::android::AttachCurrentThread(), java_delegate_.obj());
+
+  if (!callback_.is_null())
+    callback_.Run(false);
 }
 
 int PermissionUpdateInfoBarDelegate::GetIconId() const {
@@ -167,6 +173,15 @@ bool PermissionUpdateInfoBarDelegate::Accept() {
 }
 
 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);
+}