Revert 232274 "Reland "Enable SysInfo::AmountOfPhysicalMemory to..."

Broke all linux dbg layout tests (again):
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20%28dbg%29/builds/14495

> Reland "Enable SysInfo::AmountOfPhysicalMemory to be called from within the Linux Sandbox"
> 
> Trigger caching of SysInfo::AmountOfPhysicalMemory in PreSandboxInit() to enable
> it to be called by the renderer process after the sandbox is sealed.
> 
> BUG=312241
> 
> Review URL: https://codereview.chromium.org/52403002

TBR=rmcilroy@chromium.org

Review URL: https://codereview.chromium.org/54923005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232282 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232282