commit 852e4a1ef17e19ea5f57072f1ea3779107e7dce2 Author: Kathy Brade <brade@pearlcrescent.com> Date: Wed Sep 20 09:26:21 2017 -0400 squash! Bug 6253: Add canvas image extraction prompt. When processing the ShowCanvasPermissionPrompt message in the main (parent) process, avoid returning an error from the IPC handler if the browser element cannot be obtained. Prior to this change, canvas prompt requests that arrived as a tab was closing would generate an error, which in turn caused the main process to kill the content process. --- dom/ipc/TabParent.cpp | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/dom/ipc/TabParent.cpp b/dom/ipc/TabParent.cpp index ff1b41afafdb..9731561ce0b3 100644 --- a/dom/ipc/TabParent.cpp +++ b/dom/ipc/TabParent.cpp @@ -3281,7 +3281,12 @@ bool TabParent::RecvShowCanvasPermissionPrompt(const nsCString& firstPartyURI) { nsCOMPtr<nsIBrowser> browser = do_QueryInterface(mFrameElement); - NS_ENSURE_TRUE(browser, false); + if (!browser) { + // If the tab is being closed, the browser may not be available. + // In this case we can ignore the request. + return true; + } + nsCOMPtr<nsIObserverService> os = services::GetObserverService(); NS_ENSURE_TRUE(os, false); nsresult rv = os->NotifyObservers(browser, "canvas-permissions-prompt",