Instrumented libraries: add a base.isolate entry for prebuilt libs.

base/base.isolate

Index: base/base.isolate
diff --git a/base/base.isolate b/base/base.isolate
index a2458194bf382c327436065e5a115f56f284cbc0..43fca1f21bc70f373d2309e73c23e8c51b0292a4 100644
--- a/base/base.isolate
+++ b/base/base.isolate
@@ -23,6 +23,13 @@
         ],
       },
     }],
+    ['use_prebuilt_instrumented_libraries==1', {

[M-A Ruel, 2015/03/24 13:22:51]

I'm not sure it is the right place. Are these files "built" when building target
base? Same for lines 19-25.

[earthdok, 2015/03/24 13:29:29]

The files are produced by
third_party/instrumented_libraries/instrumented_libraries.gyp:(prebuilt_)instrumented_libraries,
which is a global dependency.

Actually looks like this belongs in
third_party/instrumented_libraries/instrumented_libraries.isolate? I mindlessly
added this to base.isolate because that's where other global sanitizer-related
dependencies where handled. :(

[M-A Ruel, 2015/03/24 13:31:12]

It is preferable to have the .isolate aside the .gyp that defines the target
that generates the files. So I'd like instrumented_libraries to be migrated
along.

Thanks

[earthdok, 2015/03/24 13:42:11]

Done. I should also move lines 12-17 to a separate file. I'll have to do it in a
separate CL because libc++ is located in buildtools/.

Is there a better way of introducing a global dependency other than through
base.isolate?

[M-A Ruel, 2015/03/24 13:52:09]

Ok
Patchset #4 uses the right way; the .isolate is aside the .gyp that defines the
target that generate the relevant files. base.isolate is more or less the
defacto global includes.

+      'variables': {
+        'files': [
+          '<(PRODUCT_DIR)/instrumented_libraries_prebuilt/',
+        ],
+      },
+    }],
     ['OS=="mac" and asan==1', {
       'variables': {
         'files': [