crash-reporter: Migrate libchromeos to its own ebuild

All platform2 packages should have their own ebuild that will be compiled
independently. Packages should DEPEND on libchromeos and should not have a gyp
dependency on libchromeos's gyp file anymore.

BUG=chromium:381372
TEST=emerge-daisy libchromeos && emerge-daisy platform2 work
TEST=trybot run on daisy, link, mario and duck.
TEST=trybot run on lumpy-incremental-paladin.

CQ-DEPEND=CL:202748

Change-Id: I2f6fe6e8572a533d74931db2dd850fe31d9041dc
Reviewed-on: https://chromium-review.googlesource.com/202762
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Bertrand Simonnet <bsimonnet@chromium.org>

crash-reporter.gyp

diff --git a/crash-reporter.gyp b/crash-reporter.gyp
index e1e728e..dfa95ec 100644
--- a/crash-reporter.gyp
+++ b/crash-reporter.gyp
@@ -1,9 +1,12 @@
 {
   # Shouldn't need this, but doesn't work otherwise.
-  # http://crbug.com/340086
+  # http://crbug.com/340086 and http://crbug.com/385186
+  # Note: the unused dependencies are optimized out by the compiler.
   'target_defaults': {
     'variables': {
       'deps': [
+        'libchromeos-<(libbase_ver)',
+        'dbus-glib-1',
       ],
     },
   },
@@ -33,7 +36,7 @@
         },
       },
       'dependencies': [
-        '../../platform2/libchromeos/libchromeos-<(libbase_ver).gyp:libchromeos-<(libbase_ver)',
+        '<(platform_root)/system_api/system_api.gyp:system_api-headers',
       ],
       'sources': [
         'chrome_collector.cc',
@@ -56,7 +59,6 @@
       },
       'dependencies': [
         'libcrash',
-        '../../platform2/libchromeos/libchromeos-<(libbase_ver).gyp:libchromeos-<(libbase_ver)',
         '../metrics/libmetrics-<(libbase_ver).gyp:libmetrics-<(libbase_ver)',
       ],
       'sources': [
@@ -73,9 +75,6 @@
           'libchrome-<(libbase_ver)',
         ],
       },
-      'dependencies': [
-        '../../platform2/libchromeos/libchromeos-<(libbase_ver).gyp:libchromeos-<(libbase_ver)',
-      ],
       'sources': [
         'list_proxies.cc',
       ],