Add props for content insets

Summary:
This PR adds a contentInsetStart and a contentInsetEnd property to ToolbarAndroid, allowing offsetting Toolbar contents to different keylines
Closes https://github.com/facebook/react-native/pull/4699

Reviewed By: svcscm

Differential Revision: D2759294

Pulled By: mkonicek

fb-gh-sync-id: f22aa255f07929ad7a99ac7568981d35e848065b

Libraries/Components/ToolbarAndroid/ToolbarAndroid.android.js

@@ -125,6 +125,24 @@ var ToolbarAndroid = React.createClass({
      * Sets the toolbar title color.
      */
     titleColor: ReactPropTypes.string,
+    /**
+     * Sets the content inset for the toolbar starting edge.
+     *
+     * The content inset affects the valid area for Toolbar content other than
+     * the navigation button and menu. Insets define the minimum margin for
+     * these components and can be used to effectively align Toolbar content
+     * along well-known gridlines.
+     */
+    contentInsetStart: ReactPropTypes.number,
+    /**
+     * Sets the content inset for the toolbar ending edge.
+     *
+     * The content inset affects the valid area for Toolbar content other than
+     * the navigation button and menu. Insets define the minimum margin for
+     * these components and can be used to effectively align Toolbar content
+     * along well-known gridlines.
+     */
+    contentInsetEnd: ReactPropTypes.number,
     /**
      * Used to set the toolbar direction to RTL.
      * In addition to this property you need to add

ReactAndroid/src/main/java/com/facebook/react/views/toolbar/ReactToolbarManager.java

@@ -26,6 +26,7 @@ import com.facebook.react.R;
 import com.facebook.react.bridge.ReadableArray;
 import com.facebook.react.bridge.ReadableMap;
 import com.facebook.react.common.MapBuilder;
+import com.facebook.react.uimanager.PixelUtil;
 import com.facebook.react.uimanager.ReactProp;
 import com.facebook.react.uimanager.ThemedReactContext;
 import com.facebook.react.uimanager.UIManagerModule;
@@ -100,6 +101,22 @@ public class ReactToolbarManager extends ViewGroupManager<ReactToolbar> {
     }
   }
 
+  @ReactProp(name = "contentInsetStart", defaultFloat = Float.NaN)
+  public void setContentInsetStart(ReactToolbar view, float insetStart) {
+    int inset = Float.isNaN(insetStart) ?
+        getDefaultContentInsets(view.getContext())[0] :
+        Math.round(PixelUtil.toPixelFromDIP(insetStart));
+    view.setContentInsetsRelative(inset, view.getContentInsetEnd());
+  }
+
+  @ReactProp(name = "contentInsetEnd", defaultFloat = Float.NaN)
+  public void setContentInsetEnd(ReactToolbar view, float insetEnd) {
+    int inset = Float.isNaN(insetEnd) ?
+        getDefaultContentInsets(view.getContext())[1] :
+        Math.round(PixelUtil.toPixelFromDIP(insetEnd));
+    view.setContentInsetsRelative(view.getContentInsetStart(), inset);
+  }
+
   @ReactProp(name = "nativeActions")
   public void setActions(ReactToolbar view, @Nullable ReadableArray actions) {
     view.setActions(actions);
@@ -148,6 +165,34 @@ public class ReactToolbarManager extends ViewGroupManager<ReactToolbar> {
     return true;
   }
 
+  private int[] getDefaultContentInsets(Context context) {
+    Resources.Theme theme = context.getTheme();
+    TypedArray toolbarStyle = null;
+    TypedArray contentInsets = null;
+
+    try {
+      toolbarStyle = theme
+              .obtainStyledAttributes(new int[]{R.attr.toolbarStyle});
+
+      int toolbarStyleResId = toolbarStyle.getResourceId(0, 0);
+
+      contentInsets = theme.obtainStyledAttributes(
+              toolbarStyleResId, new int[]{
+                      R.attr.contentInsetStart,
+                      R.attr.contentInsetEnd,
+              });
+
+      int contentInsetStart = contentInsets.getDimensionPixelSize(0, 0);
+      int contentInsetEnd = contentInsets.getDimensionPixelSize(1, 0);
+
+      return new int[] {contentInsetStart, contentInsetEnd};
+    } finally {
+      recycleQuietly(toolbarStyle);
+      recycleQuietly(contentInsets);
+    }
+
+  }
+
   private static int[] getDefaultColors(Context context) {
     Resources.Theme theme = context.getTheme();
     TypedArray toolbarStyle = null;