Added command buffer implementation of WebGL which runs in the sandbox.

Added synchronous initialization of the channel to the GPU process, needed
to obey WebGL startup semantics. There are problems with this on the
Windows platform which will be addressed via refactoring in the
GpuProcessHost in a subsequent CL. Implemented offscreen rendering code
path in GGL / GLES2CmdDecoder for Mac OS X.

This new code path is not yet complete for all platforms and is still being
stress tested. The previous in-process WebGL implementation is currently
used when the sandbox is disabled; it will be removed in a subsequent CL.

A one-line code change in WebKit is needed after this CL lands to enable
the new code path.

BUG=29120
TEST=ran WebGL demos on command buffer implementation on Mac

Review URL: http://codereview.chromium.org/1328001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@42879 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 68 insertions, 5 deletions

diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 92b1312..3bfc42b 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -879,6 +879,8 @@ class GLES2DecoderImpl : public base::SupportsWeakPtr<GLES2DecoderImpl>,
   HGLRC gl_context_;
   HPBUFFERARB pbuffer_;
 #elif defined(OS_MACOSX)
+  CGLContextObj gl_context_;
+  CGLPBufferObj pbuffer_;
   AcceleratedSurface surface_;
 #endif
 
@@ -1157,6 +1159,9 @@ GLES2DecoderImpl::GLES2DecoderImpl(ContextGroup* group)
       gl_device_context_(NULL),
       gl_context_(NULL),
       pbuffer_(NULL),
+#elif defined(OS_MAC)
+      gl_context_(NULL),
+      pbuffer_(NULL),
 #endif
       anti_aliased_(false) {
 }
@@ -1537,9 +1542,20 @@ bool GLES2DecoderImpl::MakeCurrent() {
   }
   return true;
 #elif defined(OS_LINUX)
+  // TODO(apatrick): offscreen rendering not yet supported on this platform.
   return window()->MakeCurrent();
 #elif defined(OS_MACOSX)
-  return surface_.MakeCurrent();
+  if (gl_context_) {
+    if (CGLGetCurrentContext() != gl_context_) {
+      if (CGLSetCurrentContext(gl_context_) != kCGLNoError) {
+        DLOG(ERROR) << "Unable to make gl context current.";
+        return false;
+      }
+    }
+    return true;
+  } else {
+    return surface_.MakeCurrent();
+  }
 #else
   NOTREACHED();
   return false;
@@ -1666,13 +1682,50 @@ bool GLES2DecoderImpl::InitPlatformSpecific() {
   if (!window()->Initialize())
     return false;
 #elif defined(OS_MACOSX)
-  // TODO(apatrick): offscreen rendering not yet supported on this platform.
-  DCHECK(!offscreen);
-
   // TODO(apatrick): parent contexts not yet supported on this platform.
   DCHECK(!parent_);
 
-  return surface_.Initialize();
+  if (offscreen) {
+    // Create a 1x1 pbuffer and associated context to bootstrap things
+    static const CGLPixelFormatAttribute attribs[] = {
+      (CGLPixelFormatAttribute) kCGLPFAPBuffer,
+      (CGLPixelFormatAttribute) 0
+    };
+    CGLPixelFormatObj pixel_format;
+    GLint num_pixel_formats;
+    if (CGLChoosePixelFormat(attribs,
+                             &pixel_format,
+                             &num_pixel_formats) != kCGLNoError) {
+      DLOG(ERROR) << "Error choosing pixel format.";
+      DestroyPlatformSpecific();
+      return false;
+    }
+    if (!pixel_format) {
+      return false;
+    }
+    CGLError res = CGLCreateContext(pixel_format, 0, &gl_context_);
+    CGLDestroyPixelFormat(pixel_format);
+    if (res != kCGLNoError) {
+      DLOG(ERROR) << "Error creating context.";
+      DestroyPlatformSpecific();
+      return false;
+    }
+    if (CGLCreatePBuffer(1, 1,
+                         GL_TEXTURE_2D, GL_RGBA,
+                         0, &pbuffer_) != kCGLNoError) {
+      DLOG(ERROR) << "Error creating pbuffer.";
+      DestroyPlatformSpecific();
+      return false;
+    }
+    if (CGLSetPBuffer(gl_context_, pbuffer_, 0, 0, 0) != kCGLNoError) {
+      DLOG(ERROR) << "Error attaching pbuffer to context.";
+      DestroyPlatformSpecific();
+      return false;
+    }
+    return true;
+  } else {
+    return surface_.Initialize();
+  }
 #endif
 
   return true;
@@ -1755,6 +1808,16 @@ void GLES2DecoderImpl::DestroyPlatformSpecific() {
     ::wglDestroyPbufferARB(pbuffer_);
     pbuffer_ = NULL;
   }
+#elif defined(OS_MAC)
+  if (gl_context_) {
+    CGLDestroyContext(gl_context_);
+    gl_context_ = NULL;
+  }
+
+  if (pbuffer_) {
+    CGLDestroyPBuffer(pbuffer_);
+    pbuffer_ = NULL;
+  }
 #endif
 }