Enable MD by default on Windows for Canary/Dev and local builds.

ui/base/material_design/material_design_controller.h

Index: ui/base/material_design/material_design_controller.h
diff --git a/ui/base/material_design/material_design_controller.h b/ui/base/material_design/material_design_controller.h
index 46363f776b1a3622726865439f3f60def1e5db5c..c18a6c1820aeb9273a8312fa8949ae906d879347 100644
--- a/ui/base/material_design/material_design_controller.h
+++ b/ui/base/material_design/material_design_controller.h
@@ -44,6 +44,11 @@ class UI_BASE_EXPORT MaterialDesignController {
   // Returns the per-platform default material design variant.
   static Mode DefaultMode();

[sky, 2016/05/13 15:49:56]

sorry, random question. Can this be private?

[Peter Kasting, 2016/05/16 19:53:16]

It's called elsewhere only by tests.  I think it's better to restrict access to
it to just testing, so I did so.

 
+  // On Windows, this should be called during startup before anyone calls any of
+  // the functions above to declare whether we should default to Material mode.
+  // TODO(pkasting): Remove this as soon as MD is on by default.
+  static void SetDefaultToMaterial(bool default_to_material);

[sky, 2016/05/13 15:49:56]

I find it mildly confusing that you expect this function to be called before
initialize. Did you consider naming this InitializeWithDefault?

[Peter Kasting, 2016/05/16 19:53:16]

You mean, by combining its functionality with Initialize()?  That's a good idea,
and will remove the need for the static variable.  Done.

+
  private:
   friend class test::MaterialDesignControllerTestAPI;
 
@@ -51,6 +56,9 @@ class UI_BASE_EXPORT MaterialDesignController {
   // reset the state back to a clean state during tear down.
   static bool is_mode_initialized_;
 
+  // True if we should default to Material mode.  Only respected on Windows.
+  static bool default_to_material_;
+
   // The current Mode to be used by the system.
   static Mode mode_;