android: Use UIResource for overscroll glow

content/browser/android/system_ui_resource.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_BROWSER_ANDROID_SYSTEM_UI_RESOURCE_H_
+#define CONTENT_BROWSER_ANDROID_SYSTEM_UI_RESOURCE_H_
+
+#include "cc/resources/ui_resource_client.h"
+#include "content/public/browser/android/ui_resource_client_android.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+
+namespace content {
+
+class UIResourceProvider;
+
+class SystemUIResourceClient {

[jdduke (slow), 2014/07/23 18:17:45]

Perhaps a comment explaining why the client is necessary (or what a typical
OnUIResourceIdChanged() response might do).

[powei, 2014/07/23 21:56:09]

Done.

+ public:
+  virtual void OnUIResourceIdChanged() = 0;
+  virtual ~SystemUIResourceClient() {}
+};
+

[jdduke (slow), 2014/07/23 18:17:45]

Maybe a brief comment or two about the purpose for this class?

[powei, 2014/07/23 21:56:08]

Done.

+class SystemUIResource : public UIResourceClientAndroid {
+ public:
+  static scoped_ptr<SystemUIResource> Create(const SkBitmap& bitmap,
+                                             UIResourceProvider* provider);
+
+  virtual ~SystemUIResource();
+
+  // cc::UIResourceClient implementation.
+  virtual cc::UIResourceBitmap GetBitmap(cc::UIResourceId uid,
+                                         bool resource_lost) OVERRIDE;
+
+  // content::UIResourceClientAndroid implementation.
+  virtual void UIResourceIsInvalid() OVERRIDE;
+
+  cc::UIResourceId id();

[jdduke (slow), 2014/07/23 18:17:45]

Looks like |id()| can be inline and const. I would move it below other public
methods.

[powei, 2014/07/23 21:56:09]

Done.

+  void Load();

[jdduke (slow), 2014/07/23 18:17:45]

It's not clear at first glance when |Load()| should be called? Or should this
method actually be private? If it should be public, maybe a note about what it
does and when to call it.

[powei, 2014/07/23 21:56:09]

Done.

+  void SetClient(SystemUIResourceClient* client);

[jdduke (slow), 2014/07/23 18:17:45]

Will the client change? Can it be set to NULL?

[powei, 2014/07/23 21:56:09]

The client will not change.  It can be set to NULL when the client goes out of
scope.

+
+ private:
+  SystemUIResource(const SkBitmap& bitmap, UIResourceProvider* provider);
+
+  SkBitmap bitmap_;
+  cc::UIResourceId id_;
+  UIResourceProvider* provider_;
+  SystemUIResourceClient* client_;
+
+  DISALLOW_COPY_AND_ASSIGN(SystemUIResource);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_ANDROID_SYSTEM_UI_RESOURCE_H_