Question: Who was replaced by Jon Walker in a band that Jake Sinclair had wrote songs for?

Context paragraphs:
Jake Sinclair (musician): Jake Sinclair (born March 7, 1985) is an American record producer, audio engineer, mixing engineer, multi-instrumentalist, vocalist, and songwriter.  His production, engineering, songwriting, and mixing credits include Weezer, Fall Out Boy, Panic!  at the Disco, 5 Seconds of Summer, Pink, New Politics, Andrew McMahon in the Wilderness, Gin Wigmore, and Train.  Sinclair co-wrote and produced Panic!  at the Disco's "Death of a Bachelor" album (which debuted at number one on the US Billboard 200) and produced Weezer's 2016 "Weezer (White Album)".  Both were nominated for Best Rock Album at the 59th Annual Grammy Awards.  He co-wrote and produced "Uma Thurman" by Fall Out Boy, which debuted at number one on the U.S. iTunes Chart, reached number 22 on the Billboard Hot 100, and was certified 2X Platinum by the RIAA in December 2015.  Sinclair received a Grammy nomination for Album of the Year for his work as engineer and bassist on Taylor Swift's "Everything Has Changed" alongside producer Butch Walker.  He co-wrote and produced the debut single, "She Looks So Perfect" by 5 Seconds of Summer that peaked at number one in over five countries and won "Song of the Year" at the 2014 ARIA Awards.  Sinclair is the former bassist of the indie/pop rock band The Films and the lead singer and producer of the indie pop duo Alohaha.

Crazy=Genius: "Crazy=Genius" is a song by American rock band Panic!  at the Disco and is the sixth track on the band's fifth studio album, "Death of a Bachelor" (2016).  It was written by Brendon Urie, Sam Hollander, and Jake Sinclair and was produced by Sinclair.  The song makes references to musicians Dennis Wilson, Brian Wilson, and Mike Love from The Beach Boys.

Bulletproof Picasso: Bulletproof Picasso is the seventh studio album by American rock band Train.  The album was released by Columbia Records in Friday-release countries on September 12, 2014, and in the United States on September 16, 2014.  It is available on CD, vinyl and as a digital download.  It is the band's first album without drummer and founding member Scott Underwood, who departed from the band before it was recorded.  It is also the band's first album since 2006's "For Me, It's You" to feature a full band line up.  The producers were Azeem, Espionage, Greg Kurstin, Jake Sinclair, Butch Walker and Whams.

The Films (band): The Films is an American indie pop rock band.  The band is originally from Charleston, South Carolina and consists of Michael Trent, Kenneth Harris, Jake Sinclair, and Adam Blake.  The band members met in high school and in 2006 recorded/produced the EP "Being Bored".  That same year, the band released their debut album "Don't Dance Rattlesnake" which earned them a substantial fan following in Germany and Japan.  Their next album "Oh, Scorpio" was released on Warner in 2009.  They toured Germany as part of the Jägermeister Rock Liga tour in 2009.

Weezer (2016 album): Weezer, also known as the White Album, is the eponymous tenth studio album by American rock band Weezer, released on April 1, 2016.  The album marks their fourth self-titled release and their first produced by Jake Sinclair.  It is the first release through Crush Music and was distributed by Atlantic Records.

Panic! at the Disco: Panic!  at the Disco is an American rock band from Las Vegas, Nevada, formed in 2004 and featuring the current lineup of vocalist Brendon Urie, accompanied on tour by bassist Dallon Weekes, guitarist Kenneth Harris and drummer Dan Pawlovich.  Founded by childhood friends Ryan Ross, Spencer Smith, Brent Wilson and Urie, Panic!  at the Disco recorded its first demos while its members were in high school.  Shortly after, the band recorded and released its debut studio album, "A Fever You Can't Sweat Out" (2005).  Popularized by the second single, "I Write Sins Not Tragedies", the album was certified double platinum in the US.  In 2006, founding bassist Brent Wilson was fired from the band during an extensive world tour and subsequently replaced by Jon Walker.

Reaper (song): "Reaper" is a song from Australian singer and songwriter Sia's seventh studio album "This Is Acting" (2016).  The song was co-written by Sia, Kanye West, Noah Goldstein, Charles Misodi Njapa (better known by his stage name 88-Keys), and Dom $olo, originally for Rihanna's album "Anti" (2016).  "Reaper" was co-produced by West, Dom $olo, Goldstein, 88-Keys, Jesse Shatkin, and Jake Sinclair.  Sia and West had previously collaborated on the latter's song "Wolves".

Nite Flights (album): Nite Flights is the sixth and last studio album by the American pop group The Walker Brothers, released in July 1978.  Each member of the group wrote songs for the album: two by Gary Walker with Scott Walker and John Walker each contributing four. " The Electrician" was released as a single from the album.

Victorious (Panic! at the Disco song): "Victorious" is a song by American rock band Panic!  at the Disco released as the second single from the band's fifth studio album, "Death of a Bachelor", on September 29, 2015 by Fueled by Ramen and DCD2.  The song was written by Brendon Urie, Christopher J Baran, Mike Viola, White Sea, Jake Sinclair, Alex DeLeon, and Rivers Cuomo and was produced by Urie and Sinclair.  A music video for the song was released on YouTube on November 13, 2015.

LA Devotee: "LA Devotee" is a song by American rock band Panic!  at the Disco.  It was released as the second promotional single from the band's fifth studio album, "Death of a Bachelor", on November 26, 2015 through Fueled by Ramen and DCD2.  The song was written by Brendon Urie, White Sea and Jake Sinclair and was produced by Sinclair.

Supporting paragraphs: Jake Sinclair (musician) Panic! at the Disco
Answer: Brent Wilson