Add GenericSharedMemoryId and use w/ GpuMemoryBuffer

content/browser/compositor/buffer_queue_unittest.cc

Index: content/browser/compositor/buffer_queue_unittest.cc
diff --git a/content/browser/compositor/buffer_queue_unittest.cc b/content/browser/compositor/buffer_queue_unittest.cc
index 4c52a8e92f55d13a6332b20fc98ae15883fc8c24..0fe4173eed2d14d0cc38f27646404b3cca5ef23a 100644
--- a/content/browser/compositor/buffer_queue_unittest.cc
+++ b/content/browser/compositor/buffer_queue_unittest.cc
@@ -34,7 +34,9 @@ class StubGpuMemoryBufferImpl : public gfx::GpuMemoryBuffer {
     return gfx::BufferFormat::RGBX_8888;
   }
   void GetStride(int* stride) const override {}
-  gfx::GpuMemoryBufferId GetId() const override { return 0; }
+  gfx::GpuMemoryBufferId GetId() const override {
+    return gfx::GpuMemoryBufferId(0);
+  }
   gfx::GpuMemoryBufferHandle GetHandle() const override {
     return gfx::GpuMemoryBufferHandle();
   }