Chromium build failed with heap leak checker, or configured with

Chromium build failed with heap leak checker, or configured with
'gyp_chromium -Dlinux_use_heapchecker=1 -Dlinux_keep_shadow_stacks=1'
parameters. This configuration set gcc option '-finstrument-functions'
and cause 'control reaches end of non-void function' error in some
sources. Some errors occur in WebKit, and this changelist doesn't
include patches for WebKit sources.

TEST=pass sync_unit_tests, browser_tests, net_unittests

Original patch by Takashi Toyoshima <toyoshim@google.com>; at
http://codereview.chromium.org/5991005/

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=71274