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+Layers History
+==============
+
+This is an overview of the major events in the history of our Layers
+infrastructure.
+
+-  iPhone released in July 2007 (Built on a toolkit called LayerKit)
+
+-  Core Animation (October 2007) LayerKit was publicly renamed to OS X
+   10.5
+
+-  Webkit CSS 3d transforms (July 2009)
+
+-  Original layers API (March 2010) Introduced the idea of a layer
+   manager that would composite. One of the first use cases for this was
+   hardware accelerated YUV conversion for video.
+
+-  Retained layers (July 7 2010 - Bug 564991) This was an important
+   concept that introduced the idea of persisting the layer content
+   across paints in gecko controlled buffers instead of just by the OS.
+   This introduced the concept of buffer rotation to deal with scrolling
+   instead of using the native scrolling APIs like ScrollWindowEx
+
+-  Layers IPC (July 2010 - Bug 570294) This introduced shadow layers and
+   edit lists and was originally done for e10s v1
+
+-  3D transforms (September 2011 - Bug 505115)
+
+-  OMTC (December 2011 - Bug 711168) This was prototyped on OS X but
+   shipped first for Fennec
+
+-  Tiling v1 (April 2012 - Bug 739679) Originally done for Fennec. This
+   was done to avoid situations where we had to do a bunch of work for
+   scrolling a small amount. i.e. buffer rotation. It allowed us to have
+   a variety of interesting features like progressive painting and lower
+   resolution painting.
+
+-  C++ Async pan zoom controller (July 2012 - Bug 750974) The existing
+   APZ code was in Java for Fennec so this was reimplemented.
+
+-  Streaming WebGL Buffers (February 2013 - Bug 716859) Infrastructure
+   to allow OMTC WebGL and avoid the need to glFinish() every frame.
+
+-  Compositor API (April 2013 - Bug 825928) The planning for this
+   started around November 2012. Layers refactoring created a compositor
+   API that abstracted away the differences between the D3D vs OpenGL.
+   The main piece of API is DrawQuad.
+
+-  Tiling v2 (Mar 7 2014 - Bug 963073) Tiling for B2G. This work is
+   mainly porting tiled layers to new textures, implementing
+   double-buffered tiles and implementing a texture client pool, to be
+   used by tiled content clients.
+
+   A large motivation for the pool was the very slow performance of
+   allocating tiles because of the sync messages to the compositor.
+
+   The slow performance of allocating was directly addressed by bug 959089
+   which allowed us to allocate gralloc buffers without sync messages to
+   the compositor thread.
+
+-  B2G WebGL performance (May 2014 - Bug 1006957, 1001417, 1024144) This
+   work improved the synchronization mechanism between the compositor
+   and the producer.