Revert 47726 (turned nacl_ui_tests red) - Mac: First steps for default plugin...

Revert 47726 (turned nacl_ui_tests red) - Mac: First steps for default plugin

BUG=17392
TEST=Go to http://www.adobe.com/shockwave/welcome/. The task manager should show that the default plugin is running, and the "Missing Plugin" text should look slightly different than it did before. (this test depends on a small webkit patch)

Requires commenting out

    if (objectContentType(url, mimeType) != ObjectContentNetscapePlugin)
        return 0;

in WebKit/WebKit/chromium/src/FrameLoaderClientImpl.cpp's createPlugin() as well, else the default plugin won't load.

Review URL: http://codereview.chromium.org/2075006

TBR=thakis@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=47730