gpu: fix gpu process crashed on win_blink_rel due to dcheck in CopyTextureCHROMIUM.

gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc

Index: gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc b/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc
index ffb9370bca76f071a1a3619a96e9a858007bafda..7a46350d984aa23947661c8c2e01b3bbc5d83fc6 100644
--- a/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc
+++ b/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc
@@ -260,8 +260,9 @@ CopyTextureCHROMIUMResourceManager::CopyTextureCHROMIUMResourceManager()
       framebuffer_(0u) {}
 
 CopyTextureCHROMIUMResourceManager::~CopyTextureCHROMIUMResourceManager() {
-  DCHECK(!buffer_id_);
-  DCHECK(!framebuffer_);
+  // |buffer_id_| and |framebuffer_| can be not-null because when GPU context is
+  // lost, this class can be deleted without releasing resources like
+  // GLES2DecoderImpl.

[piman, 2014/12/05 20:34:12]

nit: is there a way to check that the GL resources were cleared if the context
was not lost? I wouldn't want a new field introduced that we forgot to clear and
cause a leak. Since we don't track GL-level objects, it can be very hard to
detect and track down this kind of leak.

 }
 
 void CopyTextureCHROMIUMResourceManager::Initialize(