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
  CompositingRenderWidgetHostViewTabCaptureHighDPI() : kScale(2.f) {}

  CompositingRenderWidgetHostViewTabCaptureHighDPI() : kScale(2.f) {}
