Revert of Mac Overlays: Add GPU back-pressure (patchset #8 id:140001 of https://codereview.chromium.org/1273563002/ )

Reason for revert:
This broke the WebGL 2.0 prototype on Mac OS -- please see https://code.google.com/p/chromium/issues/detail?id=515696#c16 for details.

Original issue's description:
> Mac Overlays: Add GPU back-pressure
>
> Issue a GL fence after every SwapBuffers. Do not call -[CALayer
> setContents:] with the content being rendered by that SwapBuffers until
> the fence has passed.
>
> Query the previous's frame's GL fence at the beginning of each
> SwapBuffers. Also issue a callback to query the GL fence at the
> mid-point of the VSync period (if there is no subsequent SwapBuffers,
> or if the frame takes more than one VSync to render).
>
> Note that waiting for the GL fence to complete before calling -[CALayer
> setContents] is not required for correctness -- only the expected content
> (everything before the glFlush) will appear in the layer. Rather, the
> reason for waiting for the GL fence is to make the time at which the
> content will appear on-screen more reliable.
>
> Because there may be multiple calls to SwapBuffers in flight, store the
> data necessary to call -[CALayer setContents] in a PendingSwap
> structure. Maintain a queue of these structures.
>
> Because the ImageTransportSurface does not know anything about the
> VSync period, send the CGDirectDisplayID for the attached display to the
> ImageTransportSurface in the AcceleratedSurfaceMsg_BufferPresented IPC
> (which is where the CGL renderer ID is already communicated). Send this
> information instead of the raw VSync parameters so that the updates to
> all windows on a single display may be coalesced into a single callback
> in the future.
>
> Note that this display is the display that is used for vsync by the
> RenderWidgetHostViewMac, so if vsync is disabled, it will be 0.
>
> Separate gfx::ScopedSetGLToRealGLApi into its own header file to
> simplify header orders.
>
> Access the IOSurface of the GLImageIOSurface directly, rather than
> using its ScheduleOverlayPlane method. This simplifies things
> immediately, in that we can reason about the underlying IOSurface's
> lifetime better than weak pointers to images. It will also simplify
> the implementation of partial swap and multiple overlays.
>
> BUG=515696
>
> Committed: https://crrev.com/5c207cac73c835b5f362670d6b46333dfae1f4c4
> Cr-Commit-Position: refs/heads/master@{#342548}

TBR=dcheng@chromium.org,jbauman@chromium.org,tapted@chromium.org,ccameron@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=515696

Review URL: https://codereview.chromium.org/1280033004

Cr-Commit-Position: refs/heads/master@{#342566}

1 files changed, 0 insertions, 2 deletions

diff --git a/gpu/command_buffer/service/gl_context_virtual.cc b/gpu/command_buffer/service/gl_context_virtual.cc
index 563e601..f965ace 100644
--- a/gpu/command_buffer/service/gl_context_virtual.cc
+++ b/gpu/command_buffer/service/gl_context_virtual.cc
@@ -6,12 +6,10 @@
 
 #include "base/callback.h"
 #include "gpu/command_buffer/service/gl_state_restorer_impl.h"
-#include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 #include "ui/gl/gl_gl_api_implementation.h"
 #include "ui/gl/gl_surface.h"
 #include "ui/gl/gpu_preference.h"
 #include "ui/gl/gpu_timing.h"
-#include "ui/gl/scoped_api.h"
 
 namespace gpu {