We previously had a setting in chrome defaults but this deprecates that for a command line flag and…

We previously had a setting in chrome defaults but this deprecates that for a command line flag and utility function that always defers to the flag but otherwise returns a default based on operating system. The CL then removes some of the code that depended on the default for a more robust direct check by the render_view_impl. This should also help with some of the CrOS UI bugs that link disambiguation created with views that didn't necessarily initialize their RendererPreferences.

BUG=433007, 428163
TBR=jar

Review URL: https://codereview.chromium.org/725243002

Cr-Commit-Position: refs/heads/master@{#305385}
(cherry picked from commit e23094a2fb86eb15f76caf5b55927d0b7e9ba8f5)

Conflicts:
	chrome/app/generated_resources.grd
	tools/metrics/histograms/histograms.xml

Committed: https://chromium.googlesource.com/chromium/src/+/0fdf608e9339b795f23af3fd04fc7313008cd416

[luken, 2014-11-24 20:08:15]

Committed patchset #1 (id:1) manually as
0fdf608e9339b795f23af3fd04fc7313008cd416.