Revert of Upgrade ReadPixels to ES3 semantic in command buffer. (patchset #5 id:150001 of https://codereview.chromium.org/1257093004/ )

Reason for revert:
I think this is causing the Mac bots Mac 10.8 Release (Intel) and Mac 10.8 Release (ATI) to fail.
http://build.chromium.org/p/chromium.gpu/builders/Mac%2010.8%20Release%20%28ATI%29/builds/42344
The failing test is WebglConformance.conformance_context_context_hidden_alpha.

Original issue's description:
> Upgrade ReadPixels to ES3 semantic in command buffer.
>
> Move backbuffer's draw buffer setting out of context group and into per context.
>
> With this CL, ReadPixels accepts integer types in command buffer.
>
> One thing left to be dealt with is the IMPLEMENTATION_COLOR_READ_FORMAT and
> IMPLEMENTATION_COLOR_READ_TYPE.
>
> BUG=429053
> TEST=gpu_unittests, webgl 2 conformance
> R=piman@chromium.org
> NOTRY=true
>
> Committed: https://crrev.com/40baada6914eab3e953ec91b85f19585b02dafb1
> Cr-Commit-Position: refs/heads/master@{#342306}

TBR=piman@chromium.org,zmo@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=429053

Review URL: https://codereview.chromium.org/1278093002

Cr-Commit-Position: refs/heads/master@{#342312}

1 files changed, 2 insertions, 7 deletions

diff --git a/gpu/command_buffer/service/framebuffer_manager.h b/gpu/command_buffer/service/framebuffer_manager.h
index 9bf440a..a5ee819 100644
--- a/gpu/command_buffer/service/framebuffer_manager.h
+++ b/gpu/command_buffer/service/framebuffer_manager.h
@@ -116,11 +116,10 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
 
   bool HasDepthAttachment() const;
   bool HasStencilAttachment() const;
-  GLenum GetDrawBufferInternalFormat() const;
-  GLenum GetReadBufferInternalFormat() const;
+  GLenum GetColorAttachmentFormat() const;
   // If the color attachment is a texture, returns its type; otherwise,
   // returns 0.
-  GLenum GetReadBufferTextureType() const;
+  GLenum GetColorAttachmentTextureType() const;
 
   // Verify all the rules in OpenGL ES 2.0.25 4.4.5 are followed.
   // Returns GL_FRAMEBUFFER_COMPLETE if there are no reasons we know we can't
@@ -152,10 +151,6 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
   // Return true if any draw buffers has an alpha channel.
   bool HasAlphaMRT() const;
 
-  // Return false if any two active color attachments have different internal
-  // formats.
-  bool HasSameInternalFormatsMRT() const;
-
   static void ClearFramebufferCompleteComboMap();
 
   static bool AllowFramebufferComboCompleteMapForTesting() {