Automatically put all GL contexts associated with a particular GPU channel (and renderer process) in the same share group.

This is work towards allowing offscreen canvas contexts to be allocated before compositor view contexts are created. This is a problem because a canvas might be created before the window it will be displayed in exists.

This does not fix the bug on its own.

BUG=80703
Review URL: http://codereview.chromium.org/7104148

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@89395 0039d316-1c4b-4281-b951-d872f2087c98

21 files changed, 185 insertions, 83 deletions

diff --git a/ui/gfx/gl/gl.gyp b/ui/gfx/gl/gl.gyp
index 507c4e5..5da7cf3 100644
--- a/ui/gfx/gl/gl.gyp
+++ b/ui/gfx/gl/gl.gyp
@@ -74,6 +74,8 @@
         'gl_implementation_win.cc',
         'gl_interface.cc',
         'gl_interface.h',
+        'gl_share_group.cc',
+        'gl_share_group.h',
         'gl_surface.cc',
         'gl_surface.h',
         'gl_surface_linux.cc',
diff --git a/ui/gfx/gl/gl_context.cc b/ui/gfx/gl/gl_context.cc
index 9cf1e40..c19741f 100644
--- a/ui/gfx/gl/gl_context.cc
+++ b/ui/gfx/gl/gl_context.cc
@@ -13,10 +13,15 @@
 
 namespace gfx {
 
-GLContext::GLContext() {
+GLContext::GLContext(GLShareGroup* share_group) : share_group_(share_group) {
+  if (!share_group_.get())
+    share_group_ = new GLShareGroup;
+
+  share_group_->AddContext(this);
 }
 
 GLContext::~GLContext() {
+  share_group_->RemoveContext(this);
 }
 
 std::string GLContext::GetExtensions() {
@@ -35,6 +40,10 @@ bool GLContext::HasExtension(const char* name) {
   return extensions.find(delimited_name) != std::string::npos;
 }
 
+GLShareGroup* GLContext::share_group() {
+  return share_group_.get();
+}
+
 bool GLContext::LosesAllContextsOnContextLost()
 {
   switch (GetGLImplementation()) {
diff --git a/ui/gfx/gl/gl_context.h b/ui/gfx/gl/gl_context.h
index 77f167f..2159423 100644
--- a/ui/gfx/gl/gl_context.h
+++ b/ui/gfx/gl/gl_context.h
@@ -10,6 +10,7 @@
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
+#include "ui/gfx/gl/gl_share_group.h"
 
 namespace gfx {
 
@@ -18,14 +19,13 @@ class GLSurface;
 // Encapsulates an OpenGL context, hiding platform specific management.
 class GLContext : public base::RefCounted<GLContext> {
  public:
-  GLContext();
+  explicit GLContext(GLShareGroup* share_group);
 
   // Initializes the GL context to be compatible with the given surface. The GL
   // context can be made with other surface's of the same type. The compatible
   // surface is only needed for certain platforms like WGL, OSMesa and GLX. It
   // should be specific for all platforms though.
-  virtual bool Initialize(GLContext* shared_context,
-                          GLSurface* compatible_surface) = 0;
+  virtual bool Initialize(GLSurface* compatible_surface) = 0;
 
   // Destroys the GL context.
   virtual void Destroy() = 0;
@@ -53,11 +53,13 @@ class GLContext : public base::RefCounted<GLContext> {
   // context must be current.
   bool HasExtension(const char* name);
 
+  GLShareGroup* share_group();
+
   // Create a GL context that is compatible with the given surface.
-  // |share_context|, if non-NULL, is a context which the
+  // |share_group|, if non-NULL, is a group of contexts which the
   // internally created OpenGL context shares textures and other resources.
   static scoped_refptr<GLContext> CreateGLContext(
-      GLContext* shared_context,
+      GLShareGroup* share_group,
       GLSurface* compatible_surface);
 
   static bool LosesAllContextsOnContextLost();
@@ -66,6 +68,7 @@ class GLContext : public base::RefCounted<GLContext> {
   virtual ~GLContext();
 
  private:
+  scoped_refptr<GLShareGroup> share_group_;
   friend class base::RefCounted<GLContext>;
   DISALLOW_COPY_AND_ASSIGN(GLContext);
 };
diff --git a/ui/gfx/gl/gl_context_cgl.cc b/ui/gfx/gl/gl_context_cgl.cc
index 8d3d819..1629cec 100644
--- a/ui/gfx/gl/gl_context_cgl.cc
+++ b/ui/gfx/gl/gl_context_cgl.cc
@@ -10,22 +10,22 @@
 
 namespace gfx {
 
-GLContextCGL::GLContextCGL()
-  : context_(NULL) {
+GLContextCGL::GLContextCGL(GLShareGroup* share_group)
+  : GLContext(share_group),
+    context_(NULL) {
 }
 
 GLContextCGL::~GLContextCGL() {
   Destroy();
 }
 
-bool GLContextCGL::Initialize(GLContext* shared_context,
-                              GLSurface* compatible_surface) {
+bool GLContextCGL::Initialize(GLSurface* compatible_surface) {
   DCHECK(compatible_surface);
 
   CGLError res = CGLCreateContext(
       static_cast<CGLPixelFormatObj>(GLSurfaceCGL::GetPixelFormat()),
-      shared_context ?
-          static_cast<CGLContextObj>(shared_context->GetHandle()) : NULL,
+      share_group() ?
+          static_cast<CGLContextObj>(share_group()->GetHandle()) : NULL,
       reinterpret_cast<CGLContextObj*>(&context_));
   if (res != kCGLNoError) {
     LOG(ERROR) << "Error creating context.";
diff --git a/ui/gfx/gl/gl_context_cgl.h b/ui/gfx/gl/gl_context_cgl.h
index 0ebf558..14b59b3 100644
--- a/ui/gfx/gl/gl_context_cgl.h
+++ b/ui/gfx/gl/gl_context_cgl.h
@@ -11,12 +11,11 @@ class GLSurface;
 // Encapsulates a CGL OpenGL context.
 class GLContextCGL : public GLContext {
  public:
-  GLContextCGL();
+  explicit GLContextCGL(GLShareGroup* share_group);
   virtual ~GLContextCGL();
 
   // Implement GLContext.
-  virtual bool Initialize(GLContext* shared_context,
-                          GLSurface* compatible_surface);
+  virtual bool Initialize(GLSurface* compatible_surface);
   virtual void Destroy();
   virtual bool MakeCurrent(GLSurface* surface);
   virtual void ReleaseCurrent(GLSurface* surface);
diff --git a/ui/gfx/gl/gl_context_egl.cc b/ui/gfx/gl/gl_context_egl.cc
index 14701c0..63f63e9 100644
--- a/ui/gfx/gl/gl_context_egl.cc
+++ b/ui/gfx/gl/gl_context_egl.cc
@@ -32,8 +32,9 @@ std::string GLContextEGL::GetExtensions() {
   return GLContext::GetExtensions() + " " + extensions;
 }
 
-GLContextEGL::GLContextEGL()
-    : context_(NULL)
+GLContextEGL::GLContextEGL(GLShareGroup* share_group)
+    : GLContext(share_group),
+      context_(NULL)
 {
 }
 
@@ -41,8 +42,7 @@ GLContextEGL::~GLContextEGL() {
   Destroy();
 }
 
-bool GLContextEGL::Initialize(GLContext* shared_context,
-                              GLSurface* compatible_surface) {
+bool GLContextEGL::Initialize(GLSurface* compatible_surface) {
   DCHECK(compatible_surface);
   DCHECK(!context_);
 
@@ -54,7 +54,7 @@ bool GLContextEGL::Initialize(GLContext* shared_context,
   context_ = eglCreateContext(
       GLSurfaceEGL::GetDisplay(),
       GLSurfaceEGL::GetConfig(),
-      shared_context ? shared_context->GetHandle() : NULL,
+      share_group() ? share_group()->GetHandle() : NULL,
       kContextAttributes);
   if (!context_) {
     LOG(ERROR) << "eglCreateContext failed with error "
diff --git a/ui/gfx/gl/gl_context_egl.h b/ui/gfx/gl/gl_context_egl.h
index 2e8a446..f1a8193 100644
--- a/ui/gfx/gl/gl_context_egl.h
+++ b/ui/gfx/gl/gl_context_egl.h
@@ -19,12 +19,11 @@ class GLSurface;
 // Encapsulates an EGL OpenGL ES context.
 class GLContextEGL : public GLContext {
  public:
-  GLContextEGL();
+  explicit GLContextEGL(GLShareGroup* share_group);
   virtual ~GLContextEGL();
 
   // Implement GLContext.
-  virtual bool Initialize(GLContext* shared_context,
-                          GLSurface* compatible_surface);
+  virtual bool Initialize(GLSurface* compatible_surface);
   virtual void Destroy();
   virtual bool MakeCurrent(GLSurface* surface);
   virtual void ReleaseCurrent(GLSurface* surface);
diff --git a/ui/gfx/gl/gl_context_glx.cc b/ui/gfx/gl/gl_context_glx.cc
index 2625ad6..1b1a355 100644
--- a/ui/gfx/gl/gl_context_glx.cc
+++ b/ui/gfx/gl/gl_context_glx.cc
@@ -44,19 +44,21 @@ bool IsCompositingWindowManagerActive(Display* display) {
 
 }  // namespace anonymous
 
-GLContextGLX::GLContextGLX()
-  : context_(NULL) {
+GLContextGLX::GLContextGLX(GLShareGroup* share_group)
+  : GLContext(share_group),
+    context_(NULL) {
 }
 
 GLContextGLX::~GLContextGLX() {
   Destroy();
 }
 
-bool GLContextGLX::Initialize(GLContext* shared_context,
-                              GLSurface* compatible_surface) {
+bool GLContextGLX::Initialize(GLSurface* compatible_surface) {
   GLSurfaceGLX* surface_glx = static_cast<GLSurfaceGLX*>(compatible_surface);
 
   GLXFBConfig config = static_cast<GLXFBConfig>(surface_glx->GetConfig());
+  GLXContext share_handle = static_cast<GLXContext>(
+      share_group() ? share_group()->GetHandle() : NULL);
 
   // The means by which the context is created depends on whether the drawable
   // type works reliably with GLX 1.3. If it does not then fall back to GLX 1.2.
@@ -65,8 +67,7 @@ bool GLContextGLX::Initialize(GLContext* shared_context,
         GLSurfaceGLX::GetDisplay(),
         static_cast<GLXFBConfig>(surface_glx->GetConfig()),
         GLX_RGBA_TYPE,
-        static_cast<GLXContext>(
-            shared_context ? shared_context->GetHandle() : NULL),
+        share_handle,
         True);
   } else {
     Display* display = GLSurfaceGLX::GetDisplay();
@@ -94,7 +95,11 @@ bool GLContextGLX::Initialize(GLContext* shared_context,
     }
 
     // Attempt to create a context with each visual in turn until one works.
-    context_ = glXCreateContext(display, visual_info_list.get(), 0, True);
+    context_ = glXCreateContext(
+        display,
+        visual_info_list.get(),
+        share_handle,
+        True);
   }
 
   if (!context_) {
diff --git a/ui/gfx/gl/gl_context_glx.h b/ui/gfx/gl/gl_context_glx.h
index 0ee6b1a..e89bcb2 100644
--- a/ui/gfx/gl/gl_context_glx.h
+++ b/ui/gfx/gl/gl_context_glx.h
@@ -13,12 +13,11 @@ class GLSurface;
 // Encapsulates a GLX OpenGL context.
 class GLContextGLX : public GLContext {
  public:
-  GLContextGLX();
+  explicit GLContextGLX(GLShareGroup* share_group);
   virtual ~GLContextGLX();
 
   // Implement GLContext.
-  virtual bool Initialize(GLContext* shared_context,
-                          GLSurface* compatible_surface);
+  virtual bool Initialize(GLSurface* compatible_surface);
   virtual void Destroy();
   virtual bool MakeCurrent(GLSurface* surface);
   virtual void ReleaseCurrent(GLSurface* surface);
diff --git a/ui/gfx/gl/gl_context_linux.cc b/ui/gfx/gl/gl_context_linux.cc
index 8cf2eeb..238bd5f 100644
--- a/ui/gfx/gl/gl_context_linux.cc
+++ b/ui/gfx/gl/gl_context_linux.cc
@@ -20,27 +20,29 @@
 
 namespace gfx {
 
+class GLShareGroup;
+
 scoped_refptr<GLContext> GLContext::CreateGLContext(
-    GLContext* shared_context,
+    GLShareGroup* share_group,
     GLSurface* compatible_surface) {
   switch (GetGLImplementation()) {
     case kGLImplementationOSMesaGL: {
-      scoped_refptr<GLContext> context(new GLContextOSMesa);
-      if (!context->Initialize(shared_context, compatible_surface))
+      scoped_refptr<GLContext> context(new GLContextOSMesa(share_group));
+      if (!context->Initialize(compatible_surface))
         return NULL;
 
       return context;
     }
     case kGLImplementationEGLGLES2: {
-      scoped_refptr<GLContext> context(new GLContextEGL);
-      if (!context->Initialize(shared_context, compatible_surface))
+      scoped_refptr<GLContext> context(new GLContextEGL(share_group));
+      if (!context->Initialize(compatible_surface))
         return NULL;
 
       return context;
     }
     case kGLImplementationDesktopGL: {
-      scoped_refptr<GLContext> context(new GLContextGLX);
-      if (!context->Initialize(shared_context, compatible_surface))
+      scoped_refptr<GLContext> context(new GLContextGLX(share_group));
+      if (!context->Initialize(compatible_surface))
         return NULL;
 
       return context;
diff --git a/ui/gfx/gl/gl_context_mac.cc b/ui/gfx/gl/gl_context_mac.cc
index 482d93d..cdfc6f4 100644
--- a/ui/gfx/gl/gl_context_mac.cc
+++ b/ui/gfx/gl/gl_context_mac.cc
@@ -16,20 +16,22 @@
 
 namespace gfx {
 
+class GLShareGroup;
+
 scoped_refptr<GLContext> GLContext::CreateGLContext(
-    GLContext* shared_context,
+    GLShareGroup* share_group,
     GLSurface* compatible_surface) {
   switch (GetGLImplementation()) {
     case kGLImplementationDesktopGL: {
-      scoped_refptr<GLContext> context(new GLContextCGL);
-      if (!context->Initialize(shared_context, compatible_surface))
+      scoped_refptr<GLContext> context(new GLContextCGL(share_group));
+      if (!context->Initialize(compatible_surface))
         return NULL;
 
       return context;
     }
     case kGLImplementationOSMesaGL: {
-      scoped_refptr<GLContext> context(new GLContextOSMesa);
-      if (!context->Initialize(shared_context, compatible_surface))
+      scoped_refptr<GLContext> context(new GLContextOSMesa(share_group));
+      if (!context->Initialize(compatible_surface))
         return NULL;
 
       return context;
diff --git a/ui/gfx/gl/gl_context_osmesa.cc b/ui/gfx/gl/gl_context_osmesa.cc
index 5fe5150..2b45836 100644
--- a/ui/gfx/gl/gl_context_osmesa.cc
+++ b/ui/gfx/gl/gl_context_osmesa.cc
@@ -12,21 +12,20 @@
 
 namespace gfx {
 
-GLContextOSMesa::GLContextOSMesa()
-    : context_(NULL) {
+GLContextOSMesa::GLContextOSMesa(GLShareGroup* share_group)
+    : GLContext(share_group),
+      context_(NULL) {
 }
 
 GLContextOSMesa::~GLContextOSMesa() {
   Destroy();
 }
 
-bool GLContextOSMesa::Initialize(GLContext* shared_context,
-                                 GLSurface* compatible_surface) {
+bool GLContextOSMesa::Initialize(GLSurface* compatible_surface) {
   DCHECK(!context_);
 
-  OSMesaContext shared_handle = NULL;
-  if (shared_context)
-    shared_handle = static_cast<OSMesaContext>(shared_context->GetHandle());
+  OSMesaContext share_handle = static_cast<OSMesaContext>(
+      share_group() ? share_group()->GetHandle() : NULL);
 
   GLuint format =
       static_cast<GLSurfaceOSMesa*>(compatible_surface)->GetFormat();
@@ -34,7 +33,7 @@ bool GLContextOSMesa::Initialize(GLContext* shared_context,
                                     24,  // depth bits
                                     8,  // stencil bits
                                     0,  // accum bits
-                                    shared_handle);
+                                    share_handle);
   if (!context_) {
     LOG(ERROR) << "OSMesaCreateContextExt failed.";
     return false;
diff --git a/ui/gfx/gl/gl_context_osmesa.h b/ui/gfx/gl/gl_context_osmesa.h
index 633c0ad..6b4c0a9 100644
--- a/ui/gfx/gl/gl_context_osmesa.h
+++ b/ui/gfx/gl/gl_context_osmesa.h
@@ -12,17 +12,17 @@ typedef struct osmesa_context *OSMesaContext;
 
 namespace gfx {
 
+class GLShareGroup;
 class GLSurface;
 
 // Encapsulates an OSMesa OpenGL context that uses software rendering.
 class GLContextOSMesa : public GLContext {
  public:
-  GLContextOSMesa();
+  explicit GLContextOSMesa(GLShareGroup* share_group);
   virtual ~GLContextOSMesa();
 
   // Implement GLContext.
-  virtual bool Initialize(GLContext* shared_context,
-                          GLSurface* compatible_surface);
+  virtual bool Initialize(GLSurface* compatible_surface);
   virtual void Destroy();
   virtual bool MakeCurrent(GLSurface* surface);
   virtual void ReleaseCurrent(GLSurface* surface);
diff --git a/ui/gfx/gl/gl_context_stub.cc b/ui/gfx/gl/gl_context_stub.cc
index 195a396..82b7b94 100644
--- a/ui/gfx/gl/gl_context_stub.cc
+++ b/ui/gfx/gl/gl_context_stub.cc
@@ -6,14 +6,13 @@
 
 namespace gfx {
 
-GLContextStub::GLContextStub() {
+GLContextStub::GLContextStub() : GLContext(NULL) {
 }
 
 GLContextStub::~GLContextStub() {
 }
 
-bool GLContextStub::Initialize(GLContext* shared_context,
-                               GLSurface* compatible_surface) {
+bool GLContextStub::Initialize(GLSurface* compatible_surface) {
   return true;
 }
 
diff --git a/ui/gfx/gl/gl_context_stub.h b/ui/gfx/gl/gl_context_stub.h
index 58c2270..44219a2 100644
--- a/ui/gfx/gl/gl_context_stub.h
+++ b/ui/gfx/gl/gl_context_stub.h
@@ -17,8 +17,7 @@ class GLContextStub : public GLContext {
   virtual ~GLContextStub();
 
   // Implement GLContext.
-  virtual bool Initialize(GLContext* shared_context,
-                          GLSurface* compatible_surface);
+  virtual bool Initialize(GLSurface* compatible_surface);
   virtual void Destroy();
   virtual bool MakeCurrent(GLSurface* surface);
   virtual void ReleaseCurrent(GLSurface* surface);
diff --git a/ui/gfx/gl/gl_context_wgl.cc b/ui/gfx/gl/gl_context_wgl.cc
index 7df8772..8533be7 100644
--- a/ui/gfx/gl/gl_context_wgl.cc
+++ b/ui/gfx/gl/gl_context_wgl.cc
@@ -13,8 +13,9 @@
 
 namespace gfx {
 
-GLContextWGL::GLContextWGL()
-    : context_(NULL) {
+GLContextWGL::GLContextWGL(GLShareGroup* share_group)
+    : GLContext(share_group),
+      context_(NULL) {
 }
 
 GLContextWGL::~GLContextWGL() {
@@ -36,8 +37,7 @@ std::string GLContextWGL::GetExtensions() {
   return GLContext::GetExtensions();
 }
 
-bool GLContextWGL::Initialize(GLContext* shared_context,
-                              GLSurface* compatible_surface) {
+bool GLContextWGL::Initialize(GLSurface* compatible_surface) {
   GLSurfaceWGL* surface_wgl = static_cast<GLSurfaceWGL*>(compatible_surface);
 
   // TODO(apatrick): When contexts and surfaces are separated, we won't be
@@ -51,13 +51,14 @@ bool GLContextWGL::Initialize(GLContext* shared_context,
     return false;
   }
 
-  if (shared_context) {
-    if (!wglShareLists(
-        static_cast<HGLRC>(shared_context->GetHandle()),
-        context_)) {
-      LOG(ERROR) << "Could not share GL contexts.";
-      Destroy();
-      return false;
+  if (share_group()) {
+    HGLRC share_handle = static_cast<HGLRC>(share_group()->GetHandle());
+    if (share_handle) {
+      if (!wglShareLists(share_handle, context_)) {
+        LOG(ERROR) << "Could not share GL contexts.";
+        Destroy();
+        return false;
+      }
     }
   }
 
diff --git a/ui/gfx/gl/gl_context_wgl.h b/ui/gfx/gl/gl_context_wgl.h
index f48a564..3684c96 100644
--- a/ui/gfx/gl/gl_context_wgl.h
+++ b/ui/gfx/gl/gl_context_wgl.h
@@ -17,12 +17,11 @@ class GLSurface;
 // This class is a wrapper around a GL context.
 class GLContextWGL : public GLContext {
  public:
-  GLContextWGL();
+  explicit GLContextWGL(GLShareGroup* share_group);
   virtual ~GLContextWGL();
 
   // Implement GLContext.
-  virtual bool Initialize(GLContext* shared_context,
-                          GLSurface* compatible_surface);
+  virtual bool Initialize(GLSurface* compatible_surface);
   virtual void Destroy();
   virtual bool MakeCurrent(GLSurface* surface);
   virtual void ReleaseCurrent(GLSurface* surface);
diff --git a/ui/gfx/gl/gl_context_win.cc b/ui/gfx/gl/gl_context_win.cc
index c9f90706..3ca5f3b 100644
--- a/ui/gfx/gl/gl_context_win.cc
+++ b/ui/gfx/gl/gl_context_win.cc
@@ -21,26 +21,26 @@
 namespace gfx {
 
 scoped_refptr<GLContext> GLContext::CreateGLContext(
-    GLContext* shared_context,
+    GLShareGroup* share_group,
     GLSurface* compatible_surface) {
   switch (GetGLImplementation()) {
     case kGLImplementationOSMesaGL: {
-      scoped_refptr<GLContext> context(new GLContextOSMesa);
-      if (!context->Initialize(shared_context, compatible_surface))
+      scoped_refptr<GLContext> context(new GLContextOSMesa(share_group));
+      if (!context->Initialize(compatible_surface))
         return NULL;
 
       return context;
     }
     case kGLImplementationEGLGLES2: {
-      scoped_refptr<GLContext> context(new GLContextEGL);
-      if (!context->Initialize(shared_context, compatible_surface))
+      scoped_refptr<GLContext> context(new GLContextEGL(share_group));
+      if (!context->Initialize(compatible_surface))
         return NULL;
 
       return context;
     }
     case kGLImplementationDesktopGL: {
-      scoped_refptr<GLContext> context(new GLContextWGL);
-      if (!context->Initialize(shared_context, compatible_surface))
+      scoped_refptr<GLContext> context(new GLContextWGL(share_group));
+      if (!context->Initialize(compatible_surface))
         return NULL;
 
       return context;
diff --git a/ui/gfx/gl/gl_share_group.cc b/ui/gfx/gl/gl_share_group.cc
new file mode 100644
index 0000000..fa2bfcb
--- /dev/null
+++ b/ui/gfx/gl/gl_share_group.cc
@@ -0,0 +1,36 @@
+// Copyright (c) 2011 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.
+
+#include "ui/gfx/gl/gl_share_group.h"
+
+#include "ui/gfx/gl/gl_context.h"
+
+namespace gfx {
+
+GLShareGroup::GLShareGroup() {
+}
+
+void GLShareGroup::AddContext(GLContext* context) {
+  contexts_.insert(context);
+}
+
+void GLShareGroup::RemoveContext(GLContext* context) {
+  contexts_.erase(context);
+}
+
+void* GLShareGroup::GetHandle() {
+  for (ContextSet::iterator it = contexts_.begin();
+       it != contexts_.end();
+       ++it) {
+     if ((*it)->GetHandle())
+       return (*it)->GetHandle();
+  }
+
+  return NULL;
+}
+
+GLShareGroup::~GLShareGroup() {
+}
+
+}  // namespace gfx
diff --git a/ui/gfx/gl/gl_share_group.h b/ui/gfx/gl/gl_share_group.h
new file mode 100644
index 0000000..33bebb9
--- /dev/null
+++ b/ui/gfx/gl/gl_share_group.h
@@ -0,0 +1,45 @@
+// Copyright (c) 2011 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_GFX_GL_GL_SHARE_GROUP_H_
+#define UI_GFX_GL_GL_SHARE_GROUP_H_
+#pragma once
+
+#include <set>
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+
+namespace gfx {
+
+class GLContext;
+
+// A group of GL contexts that share an ID namespace.
+class GLShareGroup : public base::RefCounted<GLShareGroup> {
+ public:
+  GLShareGroup();
+
+  // These two should only be called from the constructor and destructor of
+  // GLContext.
+  void AddContext(GLContext* context);
+  void RemoveContext(GLContext* context);
+
+  // Returns a handle to any initialized context in the share group or NULL if
+  // there are no initialized contexts in the share group.
+  void* GetHandle();
+
+ private:
+  friend class base::RefCounted<GLShareGroup>;
+  ~GLShareGroup();
+
+  // References to GLContext are by raw pointer to avoid a reference count
+  // cycle.
+  typedef std::set<GLContext*> ContextSet;
+  ContextSet contexts_;
+  DISALLOW_COPY_AND_ASSIGN(GLShareGroup);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_GL_GL_SHARE_GROUP_H_
diff --git a/ui/gfx/surface/accelerated_surface_mac.cc b/ui/gfx/surface/accelerated_surface_mac.cc
index ce2f7a0..123e907 100644
--- a/ui/gfx/surface/accelerated_surface_mac.cc
+++ b/ui/gfx/surface/accelerated_surface_mac.cc
@@ -7,6 +7,7 @@
 #include "base/logging.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "ui/gfx/gl/gl_bindings.h"
+#include "ui/gfx/gl/gl_context.h"
 #include "ui/gfx/gl/gl_implementation.h"
 #include "ui/gfx/gl/gl_surface.h"
 #include "ui/gfx/rect.h"
@@ -41,7 +42,10 @@ bool AcceleratedSurface::Initialize(gfx::GLContext* share_context,
     return false;
   }
 
-  gl_context_ = gfx::GLContext::CreateGLContext(share_context,
+  gfx::GLShareGroup* share_group =
+      share_context ? share_context->share_group() : NULL;
+
+  gl_context_ = gfx::GLContext::CreateGLContext(share_group,
                                                 gl_surface_.get());
   if (!gl_context_.get()) {
     Destroy();