Allow background tab titles to use LCD AA.

ui/compositor/compositing_recorder.h

 // Copyright 2015 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 UI_COMPOSITOR_COMPOSITING_RECORDER_H_
 #define UI_COMPOSITOR_COMPOSITING_RECORDER_H_
 
 #include "base/basictypes.h"
 #include "base/macros.h"
 #include "ui/compositor/compositor_export.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace gfx {
 class Size;
 }
 
 namespace ui {
 class PaintContext;
 
 // A class to provide scoped compositing filters (eg opacity) of painting to a
 // DisplayItemList. The filters provided will be applied to any
 // DisplayItems added to the DisplayItemList while this object is alive. In
 // other words, any nested PaintRecorders or other such Recorders will
 // be filtered by the effect.
 class COMPOSITOR_EXPORT CompositingRecorder {
  public:
   // |alpha| is a value between 0 and 255, where 0 is transparent and 255 is
   // opaque. |size_in_context| is the size in the |context|'s space surrounding
-  // everything that's visible.
+  // everything that's visible.  |lcd_text_requires_opaque_layer| should
+  // normally be true; if this is false, Skia will respect text rendering
+  // requests for LCD AA even if they occur on non-opaque layers.  This should
+  // only be used in cases where the text is known to be rendered opaquely on an
+  // opaque background before compositing.
   CompositingRecorder(const PaintContext& context,
                       const gfx::Size& size_in_context,
-                      uint8_t alpha);
+                      uint8_t alpha,
+                      bool lcd_text_requires_opaque_layer);
   ~CompositingRecorder();
 
  private:
   const PaintContext& context_;
   const gfx::Rect bounds_in_layer_;
   bool saved_;
 
   DISALLOW_COPY_AND_ASSIGN(CompositingRecorder);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_CLIP_TRANSFORM_RECORDER_H_