diff --git a/modules/camera/3_4/Android.mk b/modules/camera/3_4/Android.mk
index 1ced4a5..b6f0fa6 100644
--- a/modules/camera/3_4/Android.mk
+++ b/modules/camera/3_4/Android.mk
@@ -39,6 +39,7 @@
 
 v4l2_src_files := \
   camera.cpp \
+  metadata/metadata.cpp \
   stream.cpp \
   stream_format.cpp \
   v4l2_camera.cpp \
@@ -48,7 +49,7 @@
   v4l2_wrapper.cpp \
 
 v4l2_test_files := \
-  v4l2_metadata_test.cpp \
+  metadata/metadata_test.cpp \
 
 # V4L2 Camera HAL.
 # ==============================================================================
diff --git a/modules/camera/3_4/metadata/metadata.cpp b/modules/camera/3_4/metadata/metadata.cpp
new file mode 100644
index 0000000..8867e4d
--- /dev/null
+++ b/modules/camera/3_4/metadata/metadata.cpp
@@ -0,0 +1,139 @@
+/*
+ * Copyright 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "metadata.h"
+
+#include <camera/CameraMetadata.h>
+
+#include "../common.h"
+
+namespace v4l2_camera_hal {
+
+Metadata::Metadata() { HAL_LOG_ENTER(); }
+
+Metadata::~Metadata() { HAL_LOG_ENTER(); }
+
+void Metadata::AddComponent(
+    std::unique_ptr<PartialMetadataInterface> component) {
+  HAL_LOG_ENTER();
+
+  components_.push_back(std::move(component));
+}
+
+int Metadata::FillStaticMetadata(camera_metadata_t** metadata) {
+  HAL_LOG_ENTER();
+
+  std::vector<int32_t> static_tags;
+  std::vector<int32_t> control_tags;
+  std::vector<int32_t> dynamic_tags;
+  int res = 0;
+
+  for (auto& component : components_) {
+    // Populate the fields.
+    res = component->PopulateStaticFields(metadata);
+    if (res) {
+      // Exit on error.
+      HAL_LOGE("Failed to get all static properties.");
+      return res;
+    }
+
+    // Note what tags the component adds.
+    const std::vector<int32_t>* tags = &component->StaticTags();
+    static_tags.insert(static_tags.end(), tags->begin(), tags->end());
+    tags = &component->ControlTags();
+    control_tags.insert(control_tags.end(), tags->begin(), tags->end());
+    tags = &component->DynamicTags();
+    dynamic_tags.insert(dynamic_tags.end(), tags->begin(), tags->end());
+  }
+
+  // Populate the meta fields.
+  android::CameraMetadata metadata_wrapper(*metadata);
+  static_tags.push_back(ANDROID_REQUEST_AVAILABLE_REQUEST_KEYS);
+  res = metadata_wrapper.update(ANDROID_REQUEST_AVAILABLE_REQUEST_KEYS,
+                                control_tags.data(), control_tags.size());
+  if (res != android::OK) {
+    HAL_LOGE("Failed to add request keys meta key.");
+    return -ENODEV;
+  }
+  static_tags.push_back(ANDROID_REQUEST_AVAILABLE_RESULT_KEYS);
+  res = metadata_wrapper.update(ANDROID_REQUEST_AVAILABLE_RESULT_KEYS,
+                                dynamic_tags.data(), dynamic_tags.size());
+  if (res != android::OK) {
+    HAL_LOGE("Failed to add result keys meta key.");
+    return -ENODEV;
+  }
+  static_tags.push_back(ANDROID_REQUEST_AVAILABLE_CHARACTERISTICS_KEYS);
+  res = metadata_wrapper.update(ANDROID_REQUEST_AVAILABLE_CHARACTERISTICS_KEYS,
+                                static_tags.data(), static_tags.size());
+  if (res != android::OK) {
+    HAL_LOGE("Failed to add characteristics keys meta key.");
+    return -ENODEV;
+  }
+
+  *metadata = metadata_wrapper.release();
+  return 0;
+}
+
+bool Metadata::IsValidRequest(const camera_metadata_t* metadata) {
+  HAL_LOG_ENTER();
+
+  // Null means "use previous settings", which are inherently valid.
+  if (metadata == nullptr) return true;
+
+  for (auto& component : components_) {
+    // Check that all components support the values requested of them.
+    bool valid_request = component->SupportsRequestValues(metadata);
+    if (!valid_request) {
+      // Exit early if possible.
+      return false;
+    }
+  }
+
+  return true;
+}
+
+int Metadata::SetRequestSettings(const camera_metadata_t* metadata) {
+  HAL_LOG_ENTER();
+
+  // Null means "use previous settings".
+  if (metadata == nullptr) return 0;
+
+  for (auto& component : components_) {
+    int res = component->SetRequestValues(metadata);
+    if (res) {
+      // Exit early if possible.
+      HAL_LOGE("Failed to set all requested settings.");
+      return res;
+    }
+  }
+
+  return 0;
+}
+
+int Metadata::FillResultMetadata(camera_metadata_t** metadata) {
+  for (auto& component : components_) {
+    int res = component->PopulateDynamicFields(metadata);
+    if (res) {
+      // Exit early if possible.
+      HAL_LOGE("Failed to get all dynamic result fields.");
+      return res;
+    }
+  }
+
+  return 0;
+}
+
+}  // namespace v4l2_camera_hal
diff --git a/modules/camera/3_4/metadata/metadata.h b/modules/camera/3_4/metadata/metadata.h
new file mode 100644
index 0000000..d25a040
--- /dev/null
+++ b/modules/camera/3_4/metadata/metadata.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef V4L2_CAMERA_HAL_METADATA_H_
+#define V4L2_CAMERA_HAL_METADATA_H_
+
+#include <hardware/camera3.h>
+
+#include "../common.h"
+#include "partial_metadata_interface.h"
+
+namespace v4l2_camera_hal {
+class Metadata {
+ public:
+  Metadata();
+  virtual ~Metadata();
+
+  int FillStaticMetadata(camera_metadata_t** metadata);
+  bool IsValidRequest(const camera_metadata_t* metadata);
+  int SetRequestSettings(const camera_metadata_t* metadata);
+  int FillResultMetadata(camera_metadata_t** metadata);
+
+ protected:
+  // Helper for the child constructors to fill in metadata components.
+  void AddComponent(std::unique_ptr<PartialMetadataInterface> component);
+
+ private:
+  // The overall metadata is broken down into several distinct pieces.
+  // Note: it is undefined behavior if multiple components share tags.
+  std::vector<std::unique_ptr<PartialMetadataInterface>> components_;
+
+  friend class MetadataTest;
+
+  DISALLOW_COPY_AND_ASSIGN(Metadata);
+};
+
+}  // namespace v4l2_camera_hal
+
+#endif  // V4L2_CAMERA_HAL_V4L2_METADATA_H_
diff --git a/modules/camera/3_4/v4l2_metadata_test.cpp b/modules/camera/3_4/metadata/metadata_test.cpp
similarity index 78%
rename from modules/camera/3_4/v4l2_metadata_test.cpp
rename to modules/camera/3_4/metadata/metadata_test.cpp
index 651d48c..d7da553 100644
--- a/modules/camera/3_4/v4l2_metadata_test.cpp
+++ b/modules/camera/3_4/metadata/metadata_test.cpp
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "v4l2_metadata.h"
+#include "metadata.h"
 
 #include <memory>
 #include <set>
@@ -25,7 +25,6 @@
 #include <gtest/gtest.h>
 
 #include "metadata/partial_metadata_interface_mock.h"
-#include "v4l2_wrapper_mock.h"
 
 using testing::AtMost;
 using testing::Return;
@@ -35,23 +34,13 @@
 
 namespace v4l2_camera_hal {
 
-class V4L2MetadataTest : public Test {
+class MetadataTest : public Test {
  protected:
-  // Create a test version of V4L2Metadata with no default components.
-  class TestV4L2Metadata : public V4L2Metadata {
-   public:
-    TestV4L2Metadata(V4L2Wrapper* device) : V4L2Metadata(device){};
-
-   private:
-    void PopulateComponents() override{};
-  };
-
   virtual void SetUp() {
-    device_.reset(new V4L2WrapperMock());
-    dut_.reset(new TestV4L2Metadata(device_.get()));
+    dut_.reset(new Metadata());
 
-    component1_.reset(new PartialMetadataInterfaceMock);
-    component2_.reset(new PartialMetadataInterfaceMock);
+    component1_.reset(new PartialMetadataInterfaceMock());
+    component2_.reset(new PartialMetadataInterfaceMock());
   }
 
   // Once the component mocks have had expectations set,
@@ -65,23 +54,22 @@
 
   virtual void CompareTags(const std::set<int32_t>& expected,
                            const camera_metadata_entry_t& actual) {
-    EXPECT_EQ(expected.size(), actual.count);
+    ASSERT_EQ(expected.size(), actual.count);
     for (size_t i = 0; i < actual.count; ++i) {
       EXPECT_NE(expected.find(actual.data.i32[i]), expected.end());
     }
   }
 
   // Device under test.
-  std::unique_ptr<V4L2Metadata> dut_;
+  std::unique_ptr<Metadata> dut_;
   // Mocks.
-  std::unique_ptr<V4L2WrapperMock> device_;
   std::unique_ptr<PartialMetadataInterfaceMock> component1_;
   std::unique_ptr<PartialMetadataInterfaceMock> component2_;
   // An empty vector to use as necessary.
   std::vector<int32_t> empty_tags_;
 };
 
-TEST_F(V4L2MetadataTest, FillStaticSuccess) {
+TEST_F(MetadataTest, FillStaticSuccess) {
   android::CameraMetadata metadata(1);
   camera_metadata_t* metadata_raw = metadata.release();
 
@@ -135,7 +123,7 @@
               metadata.find(ANDROID_REQUEST_AVAILABLE_RESULT_KEYS));
 }
 
-TEST_F(V4L2MetadataTest, FillStaticFail) {
+TEST_F(MetadataTest, FillStaticFail) {
   camera_metadata_t* metadata = nullptr;
   int err = -99;
   // Order undefined, and may or may not exit early; use AtMost.
@@ -169,8 +157,8 @@
   EXPECT_EQ(dut_->FillStaticMetadata(&metadata), err);
 }
 
-TEST_F(V4L2MetadataTest, IsValidSuccess) {
-  camera_metadata_t* metadata = nullptr;
+TEST_F(MetadataTest, IsValidSuccess) {
+  android::CameraMetadata metadata(1);
 
   // Should check if all the component request values are valid.
   EXPECT_CALL(*component1_, SupportsRequestValues(_)).WillOnce(Return(true));
@@ -178,11 +166,13 @@
 
   AddComponents();
   // Should succeed.
-  EXPECT_TRUE(dut_->IsValidRequest(metadata));
+  // Note: getAndLock is a lock against pointer invalidation, not concurrency,
+  // and unlocks on object destruction.
+  EXPECT_TRUE(dut_->IsValidRequest(metadata.getAndLock()));
 }
 
-TEST_F(V4L2MetadataTest, IsValidFail) {
-  camera_metadata_t* metadata = nullptr;
+TEST_F(MetadataTest, IsValidFail) {
+  android::CameraMetadata metadata(1);
 
   // Should check if all the component request values are valid.
   // Order undefined, and may or may not exit early; use AtMost.
@@ -193,23 +183,40 @@
 
   AddComponents();
   // Should fail since one of the components failed.
-  EXPECT_FALSE(dut_->IsValidRequest(metadata));
+  // Note: getAndLock is a lock against pointer invalidation, not concurrency,
+  // and unlocks on object destruction.
+  EXPECT_FALSE(dut_->IsValidRequest(metadata.getAndLock()));
 }
 
-TEST_F(V4L2MetadataTest, SetSettingsSuccess) {
+TEST_F(MetadataTest, IsValidNull) {
   camera_metadata_t* metadata = nullptr;
 
+  // Setting null settings is a special case indicating to use the
+  // previous (valid) settings. As such it is inherently valid.
+  // Should not try to check any components.
+  EXPECT_CALL(*component1_, SupportsRequestValues(_)).Times(0);
+  EXPECT_CALL(*component2_, SupportsRequestValues(_)).Times(0);
+
+  AddComponents();
+  EXPECT_TRUE(dut_->IsValidRequest(metadata));
+}
+
+TEST_F(MetadataTest, SetSettingsSuccess) {
+  android::CameraMetadata metadata(1);
+
   // Should check if all the components set successfully.
   EXPECT_CALL(*component1_, SetRequestValues(_)).WillOnce(Return(0));
   EXPECT_CALL(*component2_, SetRequestValues(_)).WillOnce(Return(0));
 
   AddComponents();
   // Should succeed.
-  EXPECT_EQ(dut_->SetRequestSettings(metadata), 0);
+  // Note: getAndLock is a lock against pointer invalidation, not concurrency,
+  // and unlocks on object destruction.
+  EXPECT_EQ(dut_->SetRequestSettings(metadata.getAndLock()), 0);
 }
 
-TEST_F(V4L2MetadataTest, SetSettingsFail) {
-  camera_metadata_t* metadata = nullptr;
+TEST_F(MetadataTest, SetSettingsFail) {
+  android::CameraMetadata metadata(1);
   int err = -99;
 
   // Should check if all the components set successfully.
@@ -221,10 +228,25 @@
 
   AddComponents();
   // Should fail since one of the components failed.
-  EXPECT_EQ(dut_->SetRequestSettings(metadata), err);
+  // Note: getAndLock is a lock against pointer invalidation, not concurrency,
+  // and unlocks on object destruction.
+  EXPECT_EQ(dut_->SetRequestSettings(metadata.getAndLock()), err);
 }
 
-TEST_F(V4L2MetadataTest, FillResultSuccess) {
+TEST_F(MetadataTest, SetSettingsNull) {
+  camera_metadata_t* metadata = nullptr;
+
+  // Setting null settings is a special case indicating to use the
+  // previous settings. Should not try to set any components.
+  EXPECT_CALL(*component1_, SetRequestValues(_)).Times(0);
+  EXPECT_CALL(*component2_, SetRequestValues(_)).Times(0);
+
+  AddComponents();
+  // Should succeed.
+  EXPECT_EQ(dut_->SetRequestSettings(metadata), 0);
+}
+
+TEST_F(MetadataTest, FillResultSuccess) {
   camera_metadata_t* metadata = nullptr;
 
   // Should check if all the components fill results successfully.
@@ -236,7 +258,7 @@
   EXPECT_EQ(dut_->FillResultMetadata(&metadata), 0);
 }
 
-TEST_F(V4L2MetadataTest, FillResultFail) {
+TEST_F(MetadataTest, FillResultFail) {
   camera_metadata_t* metadata = nullptr;
   int err = -99;
 
diff --git a/modules/camera/3_4/v4l2_metadata.cpp b/modules/camera/3_4/v4l2_metadata.cpp
index 54d2809..0745720 100644
--- a/modules/camera/3_4/v4l2_metadata.cpp
+++ b/modules/camera/3_4/v4l2_metadata.cpp
@@ -25,119 +25,11 @@
 V4L2Metadata::V4L2Metadata(V4L2Wrapper* device) : device_(device) {
   HAL_LOG_ENTER();
 
-  PopulateComponents();
+  // TODO(b/30140438): Add all metadata components used by V4L2Camera here.
+  // Currently these are all the fixed properties. Will add the other properties
+  // as more PartialMetadata subclasses get implemented.
 }
 
 V4L2Metadata::~V4L2Metadata() { HAL_LOG_ENTER(); }
 
-void V4L2Metadata::PopulateComponents() {
-  HAL_LOG_ENTER();
-
-  // TODO(arihc): Add all default components.
-}
-
-void V4L2Metadata::AddComponent(
-    std::unique_ptr<PartialMetadataInterface> component) {
-  HAL_LOG_ENTER();
-
-  components_.push_back(std::move(component));
-}
-
-int V4L2Metadata::FillStaticMetadata(camera_metadata_t** metadata) {
-  HAL_LOG_ENTER();
-
-  std::vector<int32_t> static_tags;
-  std::vector<int32_t> control_tags;
-  std::vector<int32_t> dynamic_tags;
-  int res = 0;
-
-  for (auto& component : components_) {
-    // Populate the fields.
-    res = component->PopulateStaticFields(metadata);
-    if (res) {
-      // Exit on error.
-      HAL_LOGE("Failed to get all static properties.");
-      return res;
-    }
-
-    // Note what tags the component adds.
-    const std::vector<int32_t>* tags = &component->StaticTags();
-    static_tags.insert(static_tags.end(), tags->begin(), tags->end());
-    tags = &component->ControlTags();
-    control_tags.insert(control_tags.end(), tags->begin(), tags->end());
-    tags = &component->DynamicTags();
-    dynamic_tags.insert(dynamic_tags.end(), tags->begin(), tags->end());
-  }
-
-  // Populate the meta fields.
-  android::CameraMetadata metadata_wrapper(*metadata);
-  static_tags.push_back(ANDROID_REQUEST_AVAILABLE_REQUEST_KEYS);
-  res = metadata_wrapper.update(ANDROID_REQUEST_AVAILABLE_REQUEST_KEYS,
-                                control_tags.data(), control_tags.size());
-  if (res != android::OK) {
-    HAL_LOGE("Failed to add request keys meta key.");
-    return -ENODEV;
-  }
-  static_tags.push_back(ANDROID_REQUEST_AVAILABLE_RESULT_KEYS);
-  res = metadata_wrapper.update(ANDROID_REQUEST_AVAILABLE_RESULT_KEYS,
-                                dynamic_tags.data(), dynamic_tags.size());
-  if (res != android::OK) {
-    HAL_LOGE("Failed to add result keys meta key.");
-    return -ENODEV;
-  }
-  static_tags.push_back(ANDROID_REQUEST_AVAILABLE_CHARACTERISTICS_KEYS);
-  res = metadata_wrapper.update(ANDROID_REQUEST_AVAILABLE_CHARACTERISTICS_KEYS,
-                                static_tags.data(), static_tags.size());
-  if (res != android::OK) {
-    HAL_LOGE("Failed to add characteristics keys meta key.");
-    return -ENODEV;
-  }
-
-  *metadata = metadata_wrapper.release();
-  return 0;
-}
-
-bool V4L2Metadata::IsValidRequest(const camera_metadata_t* metadata) {
-  HAL_LOG_ENTER();
-
-  for (auto& component : components_) {
-    // Check that all components support the values requested of them.
-    bool valid_request = component->SupportsRequestValues(metadata);
-    if (!valid_request) {
-      // Exit early if possible.
-      return false;
-    }
-  }
-
-  return true;
-}
-
-int V4L2Metadata::SetRequestSettings(const camera_metadata_t* metadata) {
-  HAL_LOG_ENTER();
-
-  for (auto& component : components_) {
-    int res = component->SetRequestValues(metadata);
-    if (res) {
-      // Exit early if possible.
-      HAL_LOGE("Failed to set all requested settings.");
-      return res;
-    }
-  }
-
-  return 0;
-}
-
-int V4L2Metadata::FillResultMetadata(camera_metadata_t** metadata) {
-  for (auto& component : components_) {
-    int res = component->PopulateDynamicFields(metadata);
-    if (res) {
-      // Exit early if possible.
-      HAL_LOGE("Failed to get all dynamic result fields.");
-      return res;
-    }
-  }
-
-  return 0;
-}
-
 }  // namespace v4l2_camera_hal
diff --git a/modules/camera/3_4/v4l2_metadata.h b/modules/camera/3_4/v4l2_metadata.h
index 573154a..ff157c0 100644
--- a/modules/camera/3_4/v4l2_metadata.h
+++ b/modules/camera/3_4/v4l2_metadata.h
@@ -20,36 +20,18 @@
 #include <hardware/camera3.h>
 
 #include "common.h"
-#include "metadata/partial_metadata_interface.h"
+#include "metadata/metadata.h"
 #include "v4l2_wrapper.h"
 
 namespace v4l2_camera_hal {
-class V4L2Metadata {
+class V4L2Metadata : public Metadata {
  public:
   V4L2Metadata(V4L2Wrapper* device);
   virtual ~V4L2Metadata();
 
-  int FillStaticMetadata(camera_metadata_t** metadata);
-  bool IsValidRequest(const camera_metadata_t* metadata);
-  int SetRequestSettings(const camera_metadata_t* metadata);
-  int FillResultMetadata(camera_metadata_t** metadata);
-
- protected:
-  // Helper for the constructor to fill in metadata components.
-  // Virtual/protected so tests can subclass and override populating with mocks.
-  virtual void PopulateComponents();
-
  private:
-  // Helper for the constructor to fill in metadata components.
-  void AddComponent(std::unique_ptr<PartialMetadataInterface> component);
-
   // Access to the device.
   V4L2Wrapper* device_;
-  // The overall metadata is broken down into several distinct pieces.
-  // Note: it is undefined behavior if multiple components share tags.
-  std::vector<std::unique_ptr<PartialMetadataInterface>> components_;
-
-  friend class V4L2MetadataTest;
 
   DISALLOW_COPY_AND_ASSIGN(V4L2Metadata);
 };