Plugin Power Saver: Make PepperPluginInstanceThrottler interface public.

content/public/renderer/BUILD.gn

Index: content/public/renderer/BUILD.gn
diff --git a/content/public/renderer/BUILD.gn b/content/public/renderer/BUILD.gn
index c1b5afeba593f2455cb56fc2a82475e9072f482b..5de959beffb0671dd3e838de3c7993a910b1855c 100644
--- a/content/public/renderer/BUILD.gn
+++ b/content/public/renderer/BUILD.gn
@@ -50,4 +50,11 @@ source_set("renderer_sources") {
                     ".",
                     "//content")
   }
+
+  if (enable_plugins) {
+    sources +=
+        rebase_path(content_renderer_gypi_values.public_renderer_plugin_sources,
+                    ".",
+                    "//content")
+  }
 }