Don't show a modal permission prompt if the requesting WebContents has no tab.

chrome/browser/permissions/permission_dialog_delegate.cc

Index: chrome/browser/permissions/permission_dialog_delegate.cc
diff --git a/chrome/browser/permissions/permission_dialog_delegate.cc b/chrome/browser/permissions/permission_dialog_delegate.cc
index b8a66c86aca713c16b55c76419a8be5a7aa1dd26..cbfde51a9b9d4fb836d23ba23a9cacc17ef2a612 100644
--- a/chrome/browser/permissions/permission_dialog_delegate.cc
+++ b/chrome/browser/permissions/permission_dialog_delegate.cc
@@ -47,11 +47,17 @@ void PermissionDialogDelegate::Create(
     const PermissionSetCallback& callback) {
   DCHECK(web_contents);
 
+  // If we don't have a tab, just act as though the prompt was dismissed.
+  TabAndroid* tab = TabAndroid::FromWebContents(web_contents);
+  if (!tab) {
+    callback.Run(false, PermissionAction::DISMISSED);
+    return;
+  }
+
   // Dispatch the dialog to Java, which manages the lifetime of this object.
   new PermissionDialogDelegate(
-      web_contents,
-      PermissionInfoBarDelegate::CreateDelegate(
-          type, requesting_frame, user_gesture, profile, callback));
+      tab, PermissionInfoBarDelegate::CreateDelegate(
+               type, requesting_frame, user_gesture, profile, callback));
 }
 
 // static
@@ -59,6 +65,15 @@ void PermissionDialogDelegate::CreateMediaStreamDialog(
     content::WebContents* web_contents,
     bool user_gesture,
     std::unique_ptr<MediaStreamDevicesController> controller) {
+  DCHECK(web_contents);
+
+  // If we don't have a tab, just act as though the prompt was dismissed.
+  TabAndroid* tab = TabAndroid::FromWebContents(web_contents);
+  if (!tab) {
+    controller->Cancelled();
+    return;
+  }
+
   // Called this way because the infobar delegate has a private destructor.
   std::unique_ptr<PermissionInfoBarDelegate> infobar_delegate;
   infobar_delegate.reset(new MediaStreamInfoBarDelegateAndroid(
@@ -67,7 +82,7 @@ void PermissionDialogDelegate::CreateMediaStreamDialog(
       std::move(controller)));
 
   // Dispatch the dialog to Java, which manages the lifetime of this object.
-  new PermissionDialogDelegate(web_contents, std::move(infobar_delegate));
+  new PermissionDialogDelegate(tab, std::move(infobar_delegate));
 }
 
 // static
@@ -91,15 +106,12 @@ bool PermissionDialogDelegate::RegisterPermissionDialogDelegate(JNIEnv* env) {
 
 ScopedJavaLocalRef<jobject> PermissionDialogDelegate::CreateJavaDelegate(
     JNIEnv* env) {
-  TabAndroid* tab = TabAndroid::FromWebContents(web_contents());
-  DCHECK(tab);
-
   std::vector<int> content_settings_types{
       infobar_delegate_->content_settings_types()};
 
   return Java_PermissionDialogDelegate_create(
       env, reinterpret_cast<uintptr_t>(this),
-      tab->GetJavaObject(),
+      tab_->GetJavaObject(),
       base::android::ToJavaIntArray(env, content_settings_types).obj(),
       ResourceMapper::MapFromChromiumId(infobar_delegate_->GetIconId()),
       ConvertUTF16ToJavaString(env, infobar_delegate_->GetMessageText()),
@@ -138,8 +150,8 @@ void PermissionDialogDelegate::LinkClicked(JNIEnv* env,
   // Don't call delegate_->LinkClicked() because that relies on having an
   // InfoBarService as an owner() to open the link. That will fail since the
   // wrapped delegate has no owner (it hasn't been added as an infobar).
-  if (web_contents()) {
-    web_contents()->OpenURL(content::OpenURLParams(
+  if (tab_->web_contents()) {
+    tab_->web_contents()->OpenURL(content::OpenURLParams(
         infobar_delegate_->GetLinkURL(), content::Referrer(),
         WindowOpenDisposition::NEW_FOREGROUND_TAB, ui::PAGE_TRANSITION_LINK,
         false));
@@ -152,10 +164,10 @@ void PermissionDialogDelegate::Destroy(JNIEnv* env,
 }
 
 PermissionDialogDelegate::PermissionDialogDelegate(
-    content::WebContents* web_contents,
+    TabAndroid* tab,

[raymes, 2016/12/01 00:31:08]

Do you know how the TabAndroid lifetime works? It seems like it might be safer
to get the TabAndroid inside this class from the WebContents? We know it will
always be valid in ::CreateJavaDelegate but I'm not so sure about LinkClicked

[dominickn, 2016/12/01 01:11:54]

We already require the tab to live as long as LinkClicked; we may need to
request system permissions when the user responds to the prompt, and that
requires the Tab (see PermissionDialogController.java).

[raymes, 2016/12/01 03:22:25]

I see - a reference to the TabAndroid will get passed into the Java object which
owns this object. That makes sense.

     std::unique_ptr<PermissionInfoBarDelegate> infobar_delegate)
-    : content::WebContentsObserver(web_contents),
-      infobar_delegate_(std::move(infobar_delegate)) {
+    : tab_(tab), infobar_delegate_(std::move(infobar_delegate)) {
+  DCHECK(tab_);
   DCHECK(infobar_delegate_);
 
   // Create our Java counterpart, which manages our lifetime.