Revert the perf-regressing component of r196319.

chrome/renderer/extensions/dispatcher.cc

Index: chrome/renderer/extensions/dispatcher.cc
diff --git a/chrome/renderer/extensions/dispatcher.cc b/chrome/renderer/extensions/dispatcher.cc
index 30b65258abc6a3f7e837b3fc2debe53143140be5..8da074ce0c68621cf28033ef757625135aa0c87d 100644
--- a/chrome/renderer/extensions/dispatcher.cc
+++ b/chrome/renderer/extensions/dispatcher.cc
@@ -1028,13 +1028,29 @@ void Dispatcher::DidCreateScriptContext(
 
   GetOrCreateChrome(v8_context);
 
-  // TODO(kalman): see comment below about ExtensionAPI.
-  if (extension && !extension->is_platform_app())
-    module_system->Require("miscellaneous_bindings");
-  if (context_type != Feature::WEB_PAGE_CONTEXT)
-    module_system->Require("json");  // see paranoid comment in json.js
-
-  RegisterSchemaGeneratedBindings(module_system.get(), context);
+  // Loading JavaScript is expensive, so only run the full API bindings
+  // generation mechanisms in extension pages (NOT all web pages).
+  switch (context_type) {
+    case Feature::UNSPECIFIED_CONTEXT:
+    case Feature::WEB_PAGE_CONTEXT:
+      // TODO(kalman): see comment below about ExtensionAPI.
+      InstallBindings(module_system.get(), v8_context, "app");
+      InstallBindings(module_system.get(), v8_context, "webstore");
+      break;
+    case Feature::BLESSED_EXTENSION_CONTEXT:
+    case Feature::UNBLESSED_EXTENSION_CONTEXT:
+    case Feature::CONTENT_SCRIPT_CONTEXT:
+      if (extension && !extension->is_platform_app())
+        module_system->Require("miscellaneous_bindings");
+      module_system->Require("json");  // see paranoid comment in json.js
+
+      // TODO(kalman): move this code back out of the switch and execute it
+      // regardless of |context_type|. ExtensionAPI knows how to return the
+      // correct APIs, however, until it doesn't have a 2MB overhead we can't
+      // load it in every process.
+      RegisterSchemaGeneratedBindings(module_system.get(), context);
+      break;
+  }
 
   bool is_within_platform_app = IsWithinPlatformApp(frame);
   // Inject custom JS into the platform app context.