Allow Crashpad to build in the Chromium tree

Allow Crashpad to build in the Chromium tree.

When building in the Chromium tree, this swaps out Crashpad’s copies of
mini_chromium, gtest, and gmock for the equivalents provided by
Chromium. A GYP variable, crashpad_in_chromium, is used to determine the
behavior.

gclient doesn’t sync sub-DEPS, so when doing an in-Chromium build,
Crashpad’s copies of mini_chromium, gtest, and gmock are not available.

BUG=crashpad:12
R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/b665a0db075ee4449c09a0cee5ca4aebfb19e679

[Mark Mentovai, 2015-03-07 19:22:48]

mark@chromium.org changed reviewers:
+ rsesek@chromium.org

[Robert Sesek, 2015-03-09 18:37:19]

https://codereview.chromium.org/986033002/diff/60001/third_party/gmock/gmock.gyp
File third_party/gmock/gmock.gyp (right):

https://codereview.chromium.org/986033002/diff/60001/third_party/gmock/gmock....
third_party/gmock/gmock.gyp:201: '../../../../../testing/gmock.gyp:gmock',
This would make moving the crashpad project in upstream a little difficult, if
that ever needed to happen. Is there not a better way, even with a variable?

[Mark Mentovai, 2015-03-09 19:18:09]

https://codereview.chromium.org/986033002/diff/60001/third_party/gmock/gmock.gyp
File third_party/gmock/gmock.gyp (right):

https://codereview.chromium.org/986033002/diff/60001/third_party/gmock/gmock....
third_party/gmock/gmock.gyp:201: '../../../../../testing/gmock.gyp:gmock',
Robert Sesek wrote:
> This would make moving the crashpad project in upstream a little difficult, if
> that ever needed to happen. Is there not a better way, even with a variable?

I know, this is sucky. Variable expansions don’t work in dependencies.

[Robert Sesek, 2015-03-09 19:21:59]

LGTM I guess, then

[Mark Mentovai, 2015-03-09 19:25:48]

Committed patchset #4 (id:60001) manually as
b665a0db075ee4449c09a0cee5ca4aebfb19e679 (presubmit successful).