Fix the misalignment on CrOS of the tab background images

chrome/browser/ui/views/tabs/tab_util.cc

+// Copyright (c) 2013 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.
+
+#include "chrome/browser/ui/views/tabs/tab_util.h"
+
+#include "grit/theme_resources.h"
+#include "ui/base/theme_provider.h"
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/image/canvas_image_source.h"
+#include "ui/gfx/image/image_skia.h"
+
+namespace {
+
+// An image source used to overlay |background_id| and |background_overlay_id|
+// for GetTiledInactiveBackground().
+class TabBackgroundImageSource: public gfx::CanvasImageSource {
+ public:
+  TabBackgroundImageSource(const gfx::ImageSkia& background,
+                           const gfx::ImageSkia& overlay,
+                           int relative_y_offset,
+                           int src_x,
+                           int src_y,
+                           int dst_w,
+                           int dst_h)
+      : gfx::CanvasImageSource(gfx::Size(dst_w, dst_h), false),
+        overlay_(overlay),
+        background_(background),
+        relative_y_offset_(relative_y_offset),
+        src_x_(src_x),
+        src_y_(src_y) {
+  }
+
+  virtual ~TabBackgroundImageSource() {
+  }
+
+  // Overridden from CanvasImageSource:
+  virtual void Draw(gfx::Canvas* canvas) OVERRIDE {
+    if (!background_.isNull()) {
+      canvas->TileImageInt(background_, src_x_, src_y_ + relative_y_offset_,
+          0, 0, size().width(), size().height());
+    }
+
+    if (!overlay_.isNull()) {
+      // We do not tile |overlay_| vertically because we have always done it
+      // that way.
+      // TODO: Investigate if any themes rely on the vertical tiling behavior.
+      int dst_overlay_height = std::min(size().height() + src_y_,
+          overlay_.height());
+      canvas->TileImageInt(overlay_, src_x_, src_y_, 0, 0,
+          size().width(), dst_overlay_height);
+    }
+  }
+
+ private:
+  const gfx::ImageSkia overlay_;
+  const gfx::ImageSkia background_;
+  const int relative_y_offset_;
+  int src_x_;
+  int src_y_;
+
+  DISALLOW_COPY_AND_ASSIGN(TabBackgroundImageSource);
+};
+
+}  // namespace
+
+// static
+gfx::ImageSkia TabUtil::CreateTiledInactiveBackground(
+    ui::ThemeProvider* theme_provider,
+    int background_id,
+    int background_overlay_id,
+    int relative_y_offset,
+    int src_x,
+    int src_y,
+    int dst_w,
+    int dst_h) {
+  // Do not paint the ResourceBundle's IDR_THEME_TAB_BACKGROUND_V if the
+  // theme author provided a custom IDR_THEME_TAB_BACKGROUND_V_OVERLAY.
+  gfx::ImageSkia background;
+  if (background_overlay_id != IDR_THEME_TAB_BACKGROUND_V_OVERLAY ||
+      !theme_provider->HasCustomImage(background_overlay_id)) {
+    background = *theme_provider->GetImageSkiaNamed(background_id);
+  }
+
+  // The default theme does not provide overlay images.
+  gfx::ImageSkia background_overlay;
+  if (theme_provider->HasCustomImage(background_overlay_id)) {
+    background_overlay = *theme_provider->GetImageSkiaNamed(
+        background_overlay_id);
+  }
+
+  // The ImageSkia takes ownership of |source|.
+  TabBackgroundImageSource* source = new TabBackgroundImageSource(
+      background, background_overlay, relative_y_offset, src_x, src_y,
+      dst_w, dst_h);
+  return gfx::ImageSkia(source, source->size());
+}