Remember value of IsImplSidePaintingEnabled

Remember value of IsImplSidePaintingEnabled

Command line arguments are constant at runtime, but the function
cc::switches::IsImplSidePaintingEnabled() does two searches through
the list of arguments every time it's called, and it's called every
time we record a SkPicture.

With this patch, the function remembers the value determined by the
first call and avoids repeating the searches on subsequent calls.

BUG=311248
R=nduca@chromium.org,skyostil@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=231314

[Tom Hudson, 2013-10-25 09:56:08]

Marginal speedup for Picture::Record, but it's something that was showing up on
the CPU profiles. PTAL?

[Tom Hudson, 2013-10-25 10:03:01]

Having talked to Sami about this, I'd meant to cc: him.

[Sami, 2013-10-25 10:33:13]

A simpler way to write this would be:

namespace {
bool CheckImplSidePaintingStatus() {
  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
  [...] 
}
}

bool IsImplSidePaintingEnabled() {
  static bool enabled = CheckImplSidePaintingStatus();
  return enabled;
}

[Tom Hudson, 2013-10-25 11:09:03]

On 2013/10/25 10:33:13, Sami wrote:
> A simpler way to write this would be:

Done.

[Sami, 2013-10-25 11:12:28]

lgtm, thanks. For extra credit make this generic and convert the other getters
in this file to the same format.

[danakj, 2013-10-25 18:58:59]

On 2013/10/25 11:12:28, Sami wrote:
> lgtm, thanks. For extra credit make this generic and convert the other getters
> in this file to the same format.

+1

[danakj, 2013-10-25 18:59:59]

LGTM2

[commit-bot: I haz the power, 2013-10-28 09:12:30]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tomhudson@chromium.org/43463003/10002

[commit-bot: I haz the power, 2013-10-28 12:17:21]

Change committed as 231314