gpu: Remove WebGraphicsContext3D::makeContextCurrent() in Blink

Source/platform/graphics/ImageBuffer.cpp

Index: Source/platform/graphics/ImageBuffer.cpp
diff --git a/Source/platform/graphics/ImageBuffer.cpp b/Source/platform/graphics/ImageBuffer.cpp
index 4ea1880db0cb0eac0d88abebf9010ad21787cf92..75113aef28c8f706b23a251d8a425b7a28c5e855 100644
--- a/Source/platform/graphics/ImageBuffer.cpp
+++ b/Source/platform/graphics/ImageBuffer.cpp
@@ -180,7 +180,7 @@ bool ImageBuffer::copyToPlatformTexture(WebGraphicsContext3D* context, Platform3
     if (!provider)
         return false;
     WebGraphicsContext3D* sharedContext = provider->context3d();
-    if (!sharedContext || !sharedContext->makeContextCurrent())
+    if (!sharedContext)
         return false;
 
     OwnPtr<WebExternalTextureMailbox> mailbox = adoptPtr(new WebExternalTextureMailbox);
@@ -192,9 +192,6 @@ bool ImageBuffer::copyToPlatformTexture(WebGraphicsContext3D* context, Platform3
 
     mailbox->syncPoint = sharedContext->insertSyncPoint();
 
-    if (!context->makeContextCurrent())
-        return false;
-
     context->waitSyncPoint(mailbox->syncPoint);
     Platform3DObject sourceTexture = context->createAndConsumeTextureCHROMIUM(GL_TEXTURE_2D, mailbox->name);