Include content_shell.pak for linux and windows swarming.

Apparently these are also required for the swarming phase of
tests.

BUG=312586

R=jochen@chromium.org

Review URL: https://codereview.chromium.org/580683003

Cr-Commit-Position: refs/heads/master@{#295717}

content/content_browsertests.isolate

@@ -17,7 +17,7 @@
         ],
       },
     }],
-    ['OS=="mac"', {
+    ['OS=="linux" or OS=="mac" or OS=="win"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/content_shell.pak',

content/content_unittests.isolate

@@ -18,7 +18,7 @@
         ],
       },
     }],
-    ['OS=="mac" or OS=="win"', {
+    ['OS=="linux" or OS=="mac" or OS=="win"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/content_shell.pak',