[Swarming] Isolate sancov tool.

BUG=chromium:535160,chromium:568949
LOG=n
TBR=tandrii@chromium.org, kjellander@chromium.org

Review URL: https://codereview.chromium.org/1778313002

Cr-Commit-Position: refs/heads/master@{#34663}

build/isolate.gypi

@@ -76,6 +76,8 @@
         '--config-variable', 'icu_use_data_file_flag=0',
         '--config-variable', 'msan=<(msan)',
         '--config-variable', 'tsan=<(tsan)',
+        '--config-variable', 'coverage=<(coverage)',
+        '--config-variable', 'sanitizer_coverage=<(sanitizer_coverage)',
         '--config-variable', 'component=<(component)',
         '--config-variable', 'target_arch=<(target_arch)',
         '--config-variable', 'use_custom_libcxx=<(use_custom_libcxx)',

tools/testrunner/testrunner.isolate

@@ -11,4 +11,13 @@
       './'
     ],
   },
-}
\ No newline at end of file
+  'conditions': [
+    ['coverage==1 and sanitizer_coverage=="bb"', {
+      'variables': {
+        'files': [
+          '../../third_party/llvm/projects/compiler-rt/lib/sanitizer_common/scripts/sancov.py',
+        ],
+      },
+    }],
+  ],
+}