GPU: Keep track of the last real context and real surface made current.

This allows us to set virtual contexts current, which allows us
to restore from a GLStateRestorer in Scoped{Texture,Framebuffer}Binders
with --enable-virtual-gl-contexts.

BUG=241762,163217

Review URL: https://chromiumcodereview.appspot.com/15928002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@204500 0039d316-1c4b-4281-b951-d872f2087c98

20 files changed, 113 insertions, 62 deletions

diff --git a/ui/gl/gl_context.cc b/ui/gl/gl_context.cc
index 496ed96..1bc4d12 100644
--- a/ui/gl/gl_context.cc
+++ b/ui/gl/gl_context.cc
@@ -20,6 +20,9 @@ namespace gfx {
 namespace {
 base::LazyInstance<base::ThreadLocalPointer<GLContext> >::Leaky
     current_context_ = LAZY_INSTANCE_INITIALIZER;
+
+base::LazyInstance<base::ThreadLocalPointer<GLContext> >::Leaky
+    current_real_context_ = LAZY_INSTANCE_INITIALIZER;
 }  // namespace
 
 GLContext::GLContext(GLShareGroup* share_group) : share_group_(share_group) {
@@ -32,7 +35,7 @@ GLContext::GLContext(GLShareGroup* share_group) : share_group_(share_group) {
 GLContext::~GLContext() {
   share_group_->RemoveContext(this);
   if (GetCurrent() == this) {
-    SetCurrent(NULL, NULL);
+    SetCurrent(NULL);
   }
 }
 
@@ -90,8 +93,12 @@ GLContext* GLContext::GetCurrent() {
   return current_context_.Pointer()->Get();
 }
 
-void GLContext::SetCurrent(GLContext* context, GLSurface* surface) {
-  current_context_.Pointer()->Set(context);
+GLContext* GLContext::GetRealCurrent() {
+  return current_real_context_.Pointer()->Get();
+}
+
+void GLContext::SetCurrent(GLSurface* surface) {
+  current_context_.Pointer()->Set(surface ? this : NULL);
   GLSurface::SetCurrent(surface);
 }
 
@@ -140,4 +147,14 @@ void GLContext::SetRealGLApi() {
   SetGLToRealGLApi();
 }
 
+GLContextReal::GLContextReal(GLShareGroup* share_group)
+    : GLContext(share_group) {}
+
+GLContextReal::~GLContextReal() {}
+
+void GLContextReal::SetCurrent(GLSurface* surface) {
+  GLContext::SetCurrent(surface);
+  current_real_context_.Pointer()->Set(surface ? this : NULL);
+}
+
 }  // namespace gfx
diff --git a/ui/gl/gl_context.h b/ui/gl/gl_context.h
index dc65f64..3eb390f 100644
--- a/ui/gl/gl_context.h
+++ b/ui/gl/gl_context.h
@@ -88,6 +88,7 @@ class GL_EXPORT GLContext : public base::RefCounted<GLContext> {
 
   static bool LosesAllContextsOnContextLost();
 
+  // Returns the last GLContext made current, virtual or real.
   static GLContext* GetCurrent();
 
   virtual bool WasAllocatedUsingRobustnessExtension();
@@ -107,16 +108,22 @@ class GL_EXPORT GLContext : public base::RefCounted<GLContext> {
 
   // Sets the GL api to the real hardware API (vs the VirtualAPI)
   static void SetRealGLApi();
-  static void SetCurrent(GLContext* context, GLSurface* surface);
+  virtual void SetCurrent(GLSurface* surface);
 
   // Initialize function pointers to extension functions in the GL
   // implementation. Should be called immediately after this context is made
   // current.
   bool InitializeExtensionBindings();
 
+  // Returns the last real (non-virtual) GLContext made current.
+  static GLContext* GetRealCurrent();
+
  private:
   friend class base::RefCounted<GLContext>;
 
+  // For GetRealCurrent.
+  friend class VirtualGLApi;
+
   scoped_refptr<GLShareGroup> share_group_;
   scoped_ptr<VirtualGLApi> virtual_gl_api_;
   scoped_ptr<GLStateRestorer> state_restorer_;
@@ -124,6 +131,19 @@ class GL_EXPORT GLContext : public base::RefCounted<GLContext> {
   DISALLOW_COPY_AND_ASSIGN(GLContext);
 };
 
+class GL_EXPORT GLContextReal : public GLContext {
+ public:
+  explicit GLContextReal(GLShareGroup* share_group);
+
+ protected:
+  virtual ~GLContextReal();
+
+  virtual void SetCurrent(GLSurface* surface) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(GLContextReal);
+};
+
 }  // namespace gfx
 
 #endif  // UI_GL_GL_CONTEXT_H_
diff --git a/ui/gl/gl_context_android.cc b/ui/gl/gl_context_android.cc
index 88de4fc..552b055 100644
--- a/ui/gl/gl_context_android.cc
+++ b/ui/gl/gl_context_android.cc
@@ -19,7 +19,7 @@ namespace {
 
 // Used to render into an already current context+surface,
 // that we do not have ownership of (draw callback).
-class GLNonOwnedContext : public GLContext {
+class GLNonOwnedContext : public GLContextReal {
  public:
   GLNonOwnedContext(GLShareGroup* share_group);
 
@@ -44,10 +44,10 @@ class GLNonOwnedContext : public GLContext {
 };
 
 GLNonOwnedContext::GLNonOwnedContext(GLShareGroup* share_group)
-  : GLContext(share_group) {}
+  : GLContextReal(share_group) {}
 
 bool GLNonOwnedContext::MakeCurrent(GLSurface* surface) {
-  SetCurrent(this, surface);
+  SetCurrent(surface);
   SetRealGLApi();
   return true;
 }
diff --git a/ui/gl/gl_context_cgl.cc b/ui/gl/gl_context_cgl.cc
index a4347e9..d826d81 100644
--- a/ui/gl/gl_context_cgl.cc
+++ b/ui/gl/gl_context_cgl.cc
@@ -65,7 +65,7 @@ static CGLPixelFormatObj GetPixelFormat() {
 }
 
 GLContextCGL::GLContextCGL(GLShareGroup* share_group)
-  : GLContext(share_group),
+  : GLContextReal(share_group),
     context_(NULL),
     gpu_preference_(PreferIntegratedGpu),
     discrete_pixelformat_(NULL),
@@ -186,7 +186,7 @@ bool GLContextCGL::MakeCurrent(GLSurface* surface) {
     return false;
   }
 
-  SetCurrent(this, surface);
+  SetCurrent(surface);
   if (!InitializeExtensionBindings()) {
     ReleaseCurrent(surface);
     return false;
@@ -205,7 +205,7 @@ void GLContextCGL::ReleaseCurrent(GLSurface* surface) {
   if (!IsCurrent(surface))
     return;
 
-  SetCurrent(NULL, NULL);
+  SetCurrent(NULL);
   CGLSetCurrentContext(NULL);
 }
 
@@ -215,7 +215,7 @@ bool GLContextCGL::IsCurrent(GLSurface* surface) {
   // If our context is current then our notion of which GLContext is
   // current must be correct. On the other hand, third-party code
   // using OpenGL might change the current context.
-  DCHECK(!native_context_is_current || (GetCurrent() == this));
+  DCHECK(!native_context_is_current || (GetRealCurrent() == this));
 
   if (!native_context_is_current)
     return false;
diff --git a/ui/gl/gl_context_cgl.h b/ui/gl/gl_context_cgl.h
index 94392bb..a83eaaf 100644
--- a/ui/gl/gl_context_cgl.h
+++ b/ui/gl/gl_context_cgl.h
@@ -14,7 +14,7 @@ namespace gfx {
 class GLSurface;
 
 // Encapsulates a CGL OpenGL context.
-class GLContextCGL : public GLContext {
+class GLContextCGL : public GLContextReal {
  public:
   explicit GLContextCGL(GLShareGroup* share_group);
 
diff --git a/ui/gl/gl_context_egl.cc b/ui/gl/gl_context_egl.cc
index ee815bf..7354c7d 100644
--- a/ui/gl/gl_context_egl.cc
+++ b/ui/gl/gl_context_egl.cc
@@ -25,7 +25,7 @@ using ui::GetLastEGLErrorString;
 namespace gfx {
 
 GLContextEGL::GLContextEGL(GLShareGroup* share_group)
-    : GLContext(share_group),
+    : GLContextReal(share_group),
       context_(NULL),
       display_(NULL),
       config_(NULL),
@@ -112,7 +112,7 @@ bool GLContextEGL::MakeCurrent(GLSurface* surface) {
     return false;
   }
 
-  SetCurrent(this, surface);
+  SetCurrent(surface);
   if (!InitializeExtensionBindings()) {
     ReleaseCurrent(surface);
     return false;
@@ -138,7 +138,7 @@ void GLContextEGL::ReleaseCurrent(GLSurface* surface) {
   if (unbind_fbo_on_makecurrent_)
     glBindFramebufferEXT(GL_FRAMEBUFFER, 0);
 
-  SetCurrent(NULL, NULL);
+  SetCurrent(NULL);
   eglMakeCurrent(display_,
                  EGL_NO_SURFACE,
                  EGL_NO_SURFACE,
@@ -153,7 +153,7 @@ bool GLContextEGL::IsCurrent(GLSurface* surface) {
   // If our context is current then our notion of which GLContext is
   // current must be correct. On the other hand, third-party code
   // using OpenGL might change the current context.
-  DCHECK(!native_context_is_current || (GetCurrent() == this));
+  DCHECK(!native_context_is_current || (GetRealCurrent() == this));
 
   if (!native_context_is_current)
     return false;
diff --git a/ui/gl/gl_context_egl.h b/ui/gl/gl_context_egl.h
index f694ba2..9dd9a72 100644
--- a/ui/gl/gl_context_egl.h
+++ b/ui/gl/gl_context_egl.h
@@ -19,7 +19,7 @@ namespace gfx {
 class GLSurface;
 
 // Encapsulates an EGL OpenGL ES context.
-class GLContextEGL : public GLContext {
+class GLContextEGL : public GLContextReal {
  public:
   explicit GLContextEGL(GLShareGroup* share_group);
 
diff --git a/ui/gl/gl_context_glx.cc b/ui/gl/gl_context_glx.cc
index c47a10d..aeaf5fc 100644
--- a/ui/gl/gl_context_glx.cc
+++ b/ui/gl/gl_context_glx.cc
@@ -34,7 +34,7 @@ class ScopedPtrXFree {
 }  // namespace
 
 GLContextGLX::GLContextGLX(GLShareGroup* share_group)
-  : GLContext(share_group),
+  : GLContextReal(share_group),
     context_(NULL),
     display_(NULL) {
 }
@@ -123,7 +123,7 @@ bool GLContextGLX::MakeCurrent(GLSurface* surface) {
     return false;
   }
 
-  SetCurrent(this, surface);
+  SetCurrent(surface);
   if (!InitializeExtensionBindings()) {
     ReleaseCurrent(surface);
     Destroy();
@@ -145,7 +145,7 @@ void GLContextGLX::ReleaseCurrent(GLSurface* surface) {
   if (!IsCurrent(surface))
     return;
 
-  SetCurrent(NULL, NULL);
+  SetCurrent(NULL);
   if (!glXMakeContextCurrent(display_, 0, 0, 0))
     LOG(ERROR) << "glXMakeCurrent failed in ReleaseCurrent";
 }
@@ -157,7 +157,7 @@ bool GLContextGLX::IsCurrent(GLSurface* surface) {
   // If our context is current then our notion of which GLContext is
   // current must be correct. On the other hand, third-party code
   // using OpenGL might change the current context.
-  DCHECK(!native_context_is_current || (GetCurrent() == this));
+  DCHECK(!native_context_is_current || (GetRealCurrent() == this));
 
   if (!native_context_is_current)
     return false;
diff --git a/ui/gl/gl_context_glx.h b/ui/gl/gl_context_glx.h
index 2847881..f5f9a48 100644
--- a/ui/gl/gl_context_glx.h
+++ b/ui/gl/gl_context_glx.h
@@ -17,7 +17,7 @@ namespace gfx {
 class GLSurface;
 
 // Encapsulates a GLX OpenGL context.
-class GL_EXPORT GLContextGLX : public GLContext {
+class GL_EXPORT GLContextGLX : public GLContextReal {
  public:
   explicit GLContextGLX(GLShareGroup* share_group);
 
diff --git a/ui/gl/gl_context_nsview.h b/ui/gl/gl_context_nsview.h
index bb2aa78..f4f4df7 100644
--- a/ui/gl/gl_context_nsview.h
+++ b/ui/gl/gl_context_nsview.h
@@ -17,7 +17,7 @@ class GLSurface;
 
 // GLContextNSView encapsulates an NSView-based GLContext.  This is paired with
 // the GLSurfaceNSView class.
-class GLContextNSView : public GLContext {
+class GLContextNSView : public GLContextReal {
  public:
   explicit GLContextNSView(GLShareGroup* group);
   virtual ~GLContextNSView();
diff --git a/ui/gl/gl_context_nsview.mm b/ui/gl/gl_context_nsview.mm
index 898bf01..464ca3e 100644
--- a/ui/gl/gl_context_nsview.mm
+++ b/ui/gl/gl_context_nsview.mm
@@ -64,7 +64,7 @@ bool GLContextNSView::MakeCurrent(GLSurface* surface) {
     [context_ setView:view];
   [context_ makeCurrentContext];
 
-  SetCurrent(this, surface);
+  SetCurrent(surface);
 
   if (!surface->OnMakeCurrent(this)) {
     LOG(ERROR) << "Unable to make gl context current.";
diff --git a/ui/gl/gl_context_osmesa.cc b/ui/gl/gl_context_osmesa.cc
index 22c6c1e..71154ec 100644
--- a/ui/gl/gl_context_osmesa.cc
+++ b/ui/gl/gl_context_osmesa.cc
@@ -14,7 +14,7 @@
 namespace gfx {
 
 GLContextOSMesa::GLContextOSMesa(GLShareGroup* share_group)
-    : GLContext(share_group),
+    : GLContextReal(share_group),
       context_(NULL) {
 }
 
@@ -65,7 +65,7 @@ bool GLContextOSMesa::MakeCurrent(GLSurface* surface) {
   // Row 0 is at the top.
   OSMesaPixelStore(OSMESA_Y_UP, 0);
 
-  SetCurrent(this, surface);
+  SetCurrent(surface);
   if (!InitializeExtensionBindings()) {
     ReleaseCurrent(surface);
     return false;
@@ -84,7 +84,7 @@ void GLContextOSMesa::ReleaseCurrent(GLSurface* surface) {
   if (!IsCurrent(surface))
     return;
 
-  SetCurrent(NULL, NULL);
+  SetCurrent(NULL);
   OSMesaMakeCurrent(NULL, NULL, GL_UNSIGNED_BYTE, 0, 0);
 }
 
@@ -97,7 +97,7 @@ bool GLContextOSMesa::IsCurrent(GLSurface* surface) {
   // If our context is current then our notion of which GLContext is
   // current must be correct. On the other hand, third-party code
   // using OpenGL might change the current context.
-  DCHECK(!native_context_is_current || (GetCurrent() == this));
+  DCHECK(!native_context_is_current || (GetRealCurrent() == this));
 
   if (!native_context_is_current)
     return false;
diff --git a/ui/gl/gl_context_osmesa.h b/ui/gl/gl_context_osmesa.h
index 382e8ce..f78b525 100644
--- a/ui/gl/gl_context_osmesa.h
+++ b/ui/gl/gl_context_osmesa.h
@@ -17,7 +17,7 @@ class GLShareGroup;
 class GLSurface;
 
 // Encapsulates an OSMesa OpenGL context that uses software rendering.
-class GLContextOSMesa : public GLContext {
+class GLContextOSMesa : public GLContextReal {
  public:
   explicit GLContextOSMesa(GLShareGroup* share_group);
 
diff --git a/ui/gl/gl_context_stub.cc b/ui/gl/gl_context_stub.cc
index 2b72c8f..7c63ff2 100644
--- a/ui/gl/gl_context_stub.cc
+++ b/ui/gl/gl_context_stub.cc
@@ -6,7 +6,7 @@
 
 namespace gfx {
 
-GLContextStub::GLContextStub() : GLContext(NULL) {}
+GLContextStub::GLContextStub() : GLContextReal(NULL) {}
 
 bool GLContextStub::Initialize(
     GLSurface* compatible_surface, GpuPreference gpu_preference) {
@@ -16,12 +16,13 @@ bool GLContextStub::Initialize(
 void GLContextStub::Destroy() {}
 
 bool GLContextStub::MakeCurrent(GLSurface* surface) {
-  SetCurrent(this, surface);
+  SetCurrent(surface);
   SetRealGLApi();
   return true;
 }
 
 void GLContextStub::ReleaseCurrent(GLSurface* surface) {
+  SetCurrent(NULL);
 }
 
 bool GLContextStub::IsCurrent(GLSurface* surface) {
diff --git a/ui/gl/gl_context_stub.h b/ui/gl/gl_context_stub.h
index ba130f6..8fca5b7 100644
--- a/ui/gl/gl_context_stub.h
+++ b/ui/gl/gl_context_stub.h
@@ -10,7 +10,7 @@
 namespace gfx {
 
 // A GLContext that does nothing for unit tests.
-class GL_EXPORT GLContextStub : public GLContext {
+class GL_EXPORT GLContextStub : public GLContextReal {
  public:
   GLContextStub();
 
diff --git a/ui/gl/gl_context_wgl.cc b/ui/gl/gl_context_wgl.cc
index 916e49d..dba107b 100644
--- a/ui/gl/gl_context_wgl.cc
+++ b/ui/gl/gl_context_wgl.cc
@@ -15,7 +15,7 @@
 namespace gfx {
 
 GLContextWGL::GLContextWGL(GLShareGroup* share_group)
-    : GLContext(share_group),
+    : GLContextReal(share_group),
       context_(NULL) {
 }
 
@@ -81,7 +81,7 @@ bool GLContextWGL::MakeCurrent(GLSurface* surface) {
     return false;
   }
 
-  SetCurrent(this, surface);
+  SetCurrent(surface);
   if (!InitializeExtensionBindings()) {
     ReleaseCurrent(surface);
     return false;
@@ -100,7 +100,7 @@ void GLContextWGL::ReleaseCurrent(GLSurface* surface) {
   if (!IsCurrent(surface))
     return;
 
-  SetCurrent(NULL, NULL);
+  SetCurrent(NULL);
   wglMakeCurrent(NULL, NULL);
 }
 
@@ -111,7 +111,7 @@ bool GLContextWGL::IsCurrent(GLSurface* surface) {
   // If our context is current then our notion of which GLContext is
   // current must be correct. On the other hand, third-party code
   // using OpenGL might change the current context.
-  DCHECK(!native_context_is_current || (GetCurrent() == this));
+  DCHECK(!native_context_is_current || (GetRealCurrent() == this));
 
   if (!native_context_is_current)
     return false;
diff --git a/ui/gl/gl_context_wgl.h b/ui/gl/gl_context_wgl.h
index d3f6541..13a274b 100644
--- a/ui/gl/gl_context_wgl.h
+++ b/ui/gl/gl_context_wgl.h
@@ -15,7 +15,7 @@ namespace gfx {
 class GLSurface;
 
 // This class is a wrapper around a GL context.
-class GLContextWGL : public GLContext {
+class GLContextWGL : public GLContextReal {
  public:
   explicit GLContextWGL(GLShareGroup* share_group);
   virtual ~GLContextWGL();
diff --git a/ui/gl/gl_gl_api_implementation.cc b/ui/gl/gl_gl_api_implementation.cc
index 94166eed..65f29c6 100644
--- a/ui/gl/gl_gl_api_implementation.cc
+++ b/ui/gl/gl_gl_api_implementation.cc
@@ -254,22 +254,19 @@ bool VirtualGLApi::MakeCurrent(GLContext* virtual_context, GLSurface* surface) {
   bool switched_contexts = g_current_gl_context != this;
   GLSurface* current_surface = GLSurface::GetCurrent();
   if (switched_contexts || surface != current_surface) {
-    if (!switched_contexts && current_surface &&
-        virtual_context->IsCurrent(surface)) {
-      // MakeCurrent 'lite' path that avoids potentially expensive MakeCurrent()
-      // calls if the GLSurface uses the same underlying surface or renders to
-      // an FBO.
-      if (!surface->OnMakeCurrent(real_context_)) {
-        LOG(ERROR) << "Could not make GLSurface current.";
+    // MakeCurrent 'lite' path that avoids potentially expensive MakeCurrent()
+    // calls if the GLSurface uses the same underlying surface or renders to
+    // an FBO.
+    if (switched_contexts || !current_surface ||
+        !virtual_context->IsCurrent(surface)) {
+      if (!real_context_->MakeCurrent(surface)) {
         return false;
       }
-    } else if (!real_context_->MakeCurrent(surface)) {
-      return false;
     }
   }
 
-  DCHECK(GLSurface::GetCurrent());
-  DCHECK(real_context_->IsCurrent(GLSurface::GetCurrent()));
+  DCHECK_EQ(real_context_, GLContext::GetRealCurrent());
+  DCHECK(real_context_->IsCurrent(NULL));
   DCHECK(virtual_context->IsCurrent(surface));
 
   if (switched_contexts || virtual_context != current_context_) {
@@ -290,6 +287,12 @@ bool VirtualGLApi::MakeCurrent(GLContext* virtual_context, GLSurface* surface) {
     SetGLApi(temp);
   }
   SetGLApi(this);
+
+  virtual_context->SetCurrent(surface);
+  if (!surface->OnMakeCurrent(virtual_context)) {
+    LOG(ERROR) << "Could not make GLSurface current.";
+    return false;
+  }
   return true;
 }
 
diff --git a/ui/gl/gl_surface_egl.cc b/ui/gl/gl_surface_egl.cc
index 1073304..84efbc6 100644
--- a/ui/gl/gl_surface_egl.cc
+++ b/ui/gl/gl_surface_egl.cc
@@ -16,6 +16,7 @@
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_surface_stub.h"
+#include "ui/gl/scoped_make_current.h"
 
 #if defined(USE_X11)
 extern "C" {
@@ -410,20 +411,23 @@ bool NativeViewGLSurfaceEGL::Resize(const gfx::Size& size) {
   if (size == GetSize())
     return true;
 
+  scoped_ptr<ui::ScopedMakeCurrent> scoped_make_current;
   GLContext* current_context = GLContext::GetCurrent();
-  bool was_current = current_context && current_context->IsCurrent(this);
-  if (was_current)
+  bool was_current =
+      current_context && current_context->IsCurrent(this);
+  if (was_current) {
+    scoped_make_current.reset(
+        new ui::ScopedMakeCurrent(current_context, this));
     current_context->ReleaseCurrent(this);
+  }
 
   Destroy();
 
   if (!Initialize()) {
-    LOG(ERROR) << "Failed to resize pbuffer.";
+    LOG(ERROR) << "Failed to resize window.";
     return false;
   }
 
-  if (was_current)
-    return current_context->MakeCurrent(this);
   return true;
 }
 
@@ -554,8 +558,14 @@ bool PbufferGLSurfaceEGL::Resize(const gfx::Size& size) {
   if (size == size_)
     return true;
 
+  scoped_ptr<ui::ScopedMakeCurrent> scoped_make_current;
   GLContext* current_context = GLContext::GetCurrent();
-  bool was_current = current_context && current_context->IsCurrent(this);
+  bool was_current =
+      current_context && current_context->IsCurrent(this);
+  if (was_current) {
+    scoped_make_current.reset(
+        new ui::ScopedMakeCurrent(current_context, this));
+  }
 
   size_ = size;
 
@@ -564,9 +574,6 @@ bool PbufferGLSurfaceEGL::Resize(const gfx::Size& size) {
     return false;
   }
 
-  if (was_current)
-    return current_context->MakeCurrent(this);
-
   return true;
 }
 
diff --git a/ui/gl/gl_surface_osmesa.cc b/ui/gl/gl_surface_osmesa.cc
index 7994eec..9a556bc 100644
--- a/ui/gl/gl_surface_osmesa.cc
+++ b/ui/gl/gl_surface_osmesa.cc
@@ -6,6 +6,7 @@
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_surface_osmesa.h"
+#include "ui/gl/scoped_make_current.h"
 
 namespace gfx {
 
@@ -23,10 +24,15 @@ void GLSurfaceOSMesa::Destroy() {
 }
 
 bool GLSurfaceOSMesa::Resize(const gfx::Size& new_size) {
+  scoped_ptr<ui::ScopedMakeCurrent> scoped_make_current;
   GLContext* current_context = GLContext::GetCurrent();
-  bool was_current = current_context && current_context->IsCurrent(this);
-  if (was_current)
+  bool was_current =
+      current_context && current_context->IsCurrent(this);
+  if (was_current) {
+    scoped_make_current.reset(
+        new ui::ScopedMakeCurrent(current_context, this));
     current_context->ReleaseCurrent(this);
+  }
 
   // Preserve the old buffer.
   scoped_ptr<int32[]> old_buffer(buffer_.release());
@@ -48,9 +54,6 @@ bool GLSurfaceOSMesa::Resize(const gfx::Size& new_size) {
 
   size_ = new_size;
 
-  if (was_current)
-    return current_context->MakeCurrent(this);
-
   return true;
 }