Eliminate third_party/mojo/src from all targets' include paths

mojo/common/BUILD.gn

Index: mojo/common/BUILD.gn
diff --git a/mojo/common/BUILD.gn b/mojo/common/BUILD.gn
index 0d8f3554c06c93427b30add4c32f5f882db1e83b..51599b403301167d90d153b563cf130a717f8fb0 100644
--- a/mojo/common/BUILD.gn
+++ b/mojo/common/BUILD.gn
@@ -31,6 +31,10 @@ component("common_base") {
 
   defines = [ "MOJO_COMMON_IMPLEMENTATION" ]
 
+  public_deps = [
+    "//third_party/mojo/src/mojo/public/cpp/system",
+  ]
+
   deps = [
     "//base",
     "//base/third_party/dynamic_annotations",
@@ -39,7 +43,6 @@ component("common_base") {
     "//third_party/mojo/src/mojo/public/c/system:for_component",
     "//third_party/mojo/src/mojo/public/cpp/bindings",
     "//third_party/mojo/src/mojo/public/cpp/environment",
-    "//third_party/mojo/src/mojo/public/cpp/system",
   ]
 }