Make remaining parts of components/metrics use metrics namespace.

components/metrics/gpu/gpu_metrics_provider_unittest.cc

Index: components/metrics/gpu/gpu_metrics_provider_unittest.cc
diff --git a/components/metrics/gpu/gpu_metrics_provider_unittest.cc b/components/metrics/gpu/gpu_metrics_provider_unittest.cc
index 6624922d1040c056928191d71f31b7c69e1c01b6..64f957925b2d685cd07d1876eaba3f2ec29dbf99 100644
--- a/components/metrics/gpu/gpu_metrics_provider_unittest.cc
+++ b/components/metrics/gpu/gpu_metrics_provider_unittest.cc
@@ -50,12 +50,12 @@ class GPUMetricsProviderTest : public testing::Test {
 
 TEST_F(GPUMetricsProviderTest, ProvideSystemProfileMetrics) {
   TestGPUMetricsProvider provider;
-  metrics::ChromeUserMetricsExtension uma_proto;
+  ChromeUserMetricsExtension uma_proto;
 
   provider.ProvideSystemProfileMetrics(uma_proto.mutable_system_profile());
 
   // Check that the system profile has the correct values set.
-  const metrics::SystemProfileProto::Hardware& hardware =
+  const SystemProfileProto::Hardware& hardware =
       uma_proto.system_profile().hardware();
   EXPECT_EQ(kScreenWidth, hardware.primary_screen_width());
   EXPECT_EQ(kScreenHeight, hardware.primary_screen_height());