Move supports-high-dpi flag into registry.

Calls to SetProcessDpiAwareness need to happen immediately when the app starts. Specifically, before user profile settings have been initialized.

This patch moves the --supports-high-dpi into the registry.

BUG=339152, 149881, 160457

Review URL: https://codereview.chromium.org/153403003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256811 0039d316-1c4b-4281-b951-d872f2087c98
float GetDPIScale() {
  if (IsHighDPIEnabled()) {
    return gfx::Display::HasForceDeviceScaleFactor() ?
        gfx::Display::GetForcedDeviceScaleFactor() :
        GetUnforcedDeviceScaleFactor();
  }
   return 1.0;
 }

float GetDPIScale() {
  if (IsHighDPIEnabled()) {
    return gfx::Display::HasForceDeviceScaleFactor() ?
        gfx::Display::GetForcedDeviceScaleFactor() :
        GetUnforcedDeviceScaleFactor();
  }
   return 1.0;
 }
