Steps used to reproduce the problem are similar to what is described there: https://code.google.com/p/chromiumembedded/wiki/GeneralUsage#Custom_Implementation

What steps will reproduce the problem? 1. Register a javascript function using a callback in one of its parameters. 2. Connect through Chromedriver configured with remote debug port to the window. 3. Execute this function using a custom V8Handler to store the callback and context for a later use. 4. The render process sends an asynchronous IPC message to the browser process requesting that work be performed. 5. Upon completion of the work the browser process sends an asynchronous IPC message back to the render process with the result. 6. The render process receives the IPC message and try to executes the callback function with the result.

What is the expected output? What do you see instead? We expect callback execution, instead stored context and function are NULL, so it crashes.

What version of the product are you using? On what operating system? CEF3 branch 2171, Windows 8 64bits

Please provide any additional information below. Without connecting through Chromedriver the whole process execute normally.

In attachment, please find patch to apply on cefsimple and the index.html used to highlight the issue.

Related forum post: http://magpcss.org/ceforum/viewtopic.php?f=6&t=12712

In the forum post you say:

context is not null when executing CefV8Handler::Execute() for storing current context and callback function, but is null when using it after inter-processes communications, resulting in a crash when using Chromedriver while using callback functions.

Can you verify that V8Handler::Execute is called and that |context| and |function| are assigned values? Do you have multiple browsers in |browser_list_|?

You're not clearing the |context| and |function| values anywhere so they're likely either (a) not being assigned to begin with or (b) the calls to V8Handler::Execute and V8Handler::executeCallback are occurring in different renderer processes.

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I added logs to the patch to show function and context ptr value. Here is what is shown with my new logs:

V8Handler::Execute() : GetCurrentContext() is : not null Storing function: not null Storing context: not null

V8Handler::executeCallback() : Stored context: context is null Stored function: function is null

So V8Handler::Execute is called and |context| and |function| are both assigned values.

Running with the same logs but without connecting chromedriver, the output is:

V8Handler::Execute() : GetCurrentContext() is : not null Storing function: not null Storing context: not null

V8Handler::executeCallback() : Stored context: context is not null Stored function: function is not null

|browser_list_| is left untouched from cefsimple, so when requiring a browser I use the first one from the list, expecting to get the main and only one.

@#3: Is there anything else occurring between call to V8Handler::Execute() and V8Handler::executeCallback() (navigation, etc)? Can you print the current thread ID as part of the output from those functions?

Thread ID when executing both V8Handler::Execute() and V8Handler::executeCallback() is TID_RENDERER, chromedriver connected and not connected.

I'm not sure about what you are asking, but the only thing I'm doing is pressing the button (only element in my webpage), executing my function with a callback in its parameters, which trigger the usual IPC process.

But I can check if any other function are called in between, if that's why you are asking ?

@#5: I'd like to verify that the renderer process is not changing between calls. Please include the output of base::PlatformThread::CurrentId() (from include/base/cef_platform_thread.h) in your print statements.

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@#6: Sorry for the delay. Printing this id show:

V8Handler::Execute(): TID_RENDERER; current id: 3836 Storing function: not null Storing context: not null

V8Handler::executeCallback(): TID_RENDERER; current id: 3836 Stored function: function is null Stored context: context is null

Furthermore, the problem occur after plugging and then executing anything with Chromedriver (just plug in does not result in this issue).

First execution with Chromedriver (such as printing currentUrl with getDriver().getCurrentUrl() or anything else) flicker the webview, as if it was refreshed or reloaded, but it is not.

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