fix(toolbar): don't auto-generate first row if first row would be empty

Currently the toolbar always generates the first `<md-toolbar-row>`. This means that developers have no opportunity to set directives/attributes/classes on the first toolbar row (e.g with flex-layout).

With this change, the first toolbar row will be only auto-generated if there is user content that can be projected into the default first row. This means that developers can now do the following:

```html
<md-toolbar>
  <md-toolbar-row>First Row</md-toolbar-row>
  <md-toolbar-row>Second Row</md-toolbar-row>
</md-toolbar>
```

Fixes angular#6004. Fixes angular#1718.

src/lib/toolbar/index.ts

@@ -7,12 +7,13 @@
  */
 
 import {NgModule} from '@angular/core';
+import {PlatformModule} from '@angular/cdk/platform';
 import {MdCommonModule} from '../core';
 import {MdToolbar, MdToolbarRow} from './toolbar';
 
 
 @NgModule({
-  imports: [MdCommonModule],
+  imports: [MdCommonModule, PlatformModule],
   exports: [MdToolbar, MdToolbarRow, MdCommonModule],
   declarations: [MdToolbar, MdToolbarRow],
 })

src/lib/toolbar/toolbar.html

@@ -1,5 +1,5 @@
 <div class="mat-toolbar-layout">
-  <md-toolbar-row>
+  <md-toolbar-row #defaultFirstRow>
     <ng-content></ng-content>
   </md-toolbar-row>
   <ng-content select="md-toolbar-row, mat-toolbar-row"></ng-content>

src/lib/toolbar/toolbar.md

@@ -21,6 +21,19 @@ Each toolbar row is a `display: flex` container.
 </md-toolbar>
 ```
 
+In some situations, developers need full control over all `<md-toolbar-row>` elements
+(e.g. for use with flex-layout).
+
+To have full control over the first `<md-toolbar-row>`, which is usually auto-generated, 
+there should be only row elements in the `<md-toolbar>`.
+
+```html
+<md-toolbar>
+  <md-toolbar-row>First Row</md-toolbar-row>
+  <md-toolbar-row>Second Row</md-toolbar-row>
+</md-toolbar>
+```
+
 ### Positioning toolbar content
 The toolbar does not perform any positioning of its content. This gives the user full power to 
 position the content as it suits their application.

src/lib/toolbar/toolbar.spec.ts

@@ -3,55 +3,86 @@ import {TestBed, async, ComponentFixture} from '@angular/core/testing';
 import {By} from '@angular/platform-browser';
 import {MdToolbarModule} from './index';
 
-
 describe('MdToolbar', () => {
 
-  let fixture: ComponentFixture<TestApp>;
-  let testComponent: TestApp;
-  let toolbarElement: HTMLElement;
-
   beforeEach(async(() => {
     TestBed.configureTestingModule({
       imports: [MdToolbarModule],
-      declarations: [TestApp],
+      declarations: [ToolbarWithDefaultFirstRow, ToolbarWithoutDefaultFirstRow],
     });
 
     TestBed.compileComponents();
   }));
 
-  beforeEach(() => {
-    fixture = TestBed.createComponent(TestApp);
-    testComponent = fixture.debugElement.componentInstance;
-    toolbarElement = fixture.debugElement.query(By.css('md-toolbar')).nativeElement;
-  });
+  describe('with default first row', () => {
+    let fixture: ComponentFixture<ToolbarWithDefaultFirstRow>;
+    let testComponent: ToolbarWithDefaultFirstRow;
+    let toolbarElement: HTMLElement;
+    let toolbarRowElements: HTMLElement[];
+
+    beforeEach(() => {
+      fixture = TestBed.createComponent(ToolbarWithDefaultFirstRow);
+      testComponent = fixture.debugElement.componentInstance;
+      toolbarElement = fixture.debugElement.query(By.css('.mat-toolbar')).nativeElement;
+      toolbarRowElements = fixture.debugElement.queryAll(By.css('.mat-toolbar-row'))
+        .map(rowDebugElement => rowDebugElement.nativeElement);
+    });
 
-  it('should apply class based on color attribute', () => {
-    testComponent.toolbarColor = 'primary';
-    fixture.detectChanges();
+    it('should apply class based on color attribute', () => {
+      testComponent.toolbarColor = 'primary';
+      fixture.detectChanges();
 
-    expect(toolbarElement.classList.contains('mat-primary')).toBe(true);
+      expect(toolbarElement.classList.contains('mat-primary')).toBe(true);
 
-    testComponent.toolbarColor = 'accent';
-    fixture.detectChanges();
+      testComponent.toolbarColor = 'accent';
+      fixture.detectChanges();
 
-    expect(toolbarElement.classList.contains('mat-primary')).toBe(false);
-    expect(toolbarElement.classList.contains('mat-accent')).toBe(true);
+      expect(toolbarElement.classList.contains('mat-primary')).toBe(false);
+      expect(toolbarElement.classList.contains('mat-accent')).toBe(true);
+
+      testComponent.toolbarColor = 'warn';
+      fixture.detectChanges();
+
+      expect(toolbarElement.classList.contains('mat-accent')).toBe(false);
+      expect(toolbarElement.classList.contains('mat-warn')).toBe(true);
+    });
 
-    testComponent.toolbarColor = 'warn';
-    fixture.detectChanges();
+    it('should set the toolbar role on the host', () => {
+      expect(toolbarElement.getAttribute('role')).toBe('toolbar');
+    });
 
-    expect(toolbarElement.classList.contains('mat-accent')).toBe(false);
-    expect(toolbarElement.classList.contains('mat-warn')).toBe(true);
+    it('should generate a default first row if content is projected', () => {
+      expect(toolbarRowElements.length)
+        .toBe(2, 'Expected a default first row and a second row to be present.');
+    });
   });
 
-  it('should set the toolbar role on the host', () => {
-    expect(toolbarElement.getAttribute('role')).toBe('toolbar');
+  describe('without default first row', () => {
+
+    it('should not generate a default first row if no content is projected', () => {
+      const fixture = TestBed.createComponent(ToolbarWithoutDefaultFirstRow);
+
+      expect(fixture.debugElement.queryAll(By.css('.mat-toolbar-row')).length)
+        .toBe(2, 'Expected one toolbar row to be present while no content is projected.');
+    });
   });
 
+
 });
 
 
-@Component({template: `<md-toolbar [color]="toolbarColor">Test Toolbar</md-toolbar>`})
-class TestApp {
+@Component({template: `
+  <md-toolbar [color]="toolbarColor">
+    First Row
+    <md-toolbar-row>Second Row</md-toolbar-row>
+  </md-toolbar>`})
+class ToolbarWithDefaultFirstRow {
   toolbarColor: string;
 }
+
+@Component({template: `
+  <md-toolbar [color]="toolbarColor">
+    <md-toolbar-row>First Row</md-toolbar-row>
+  </md-toolbar>
+`})
+class ToolbarWithoutDefaultFirstRow {}

src/lib/toolbar/toolbar.ts

@@ -13,15 +13,11 @@ import {
   Directive,
   ElementRef,
   Renderer2,
+  ViewChild,
+  AfterViewInit,
 } from '@angular/core';
 import {CanColor, mixinColor} from '../core/common-behaviors/color';
-
-
-@Directive({
-  selector: 'md-toolbar-row, mat-toolbar-row',
-  host: {'class': 'mat-toolbar-row'},
-})
-export class MdToolbarRow {}
+import {Platform} from '@angular/cdk/platform';
 
 // Boilerplate for applying mixins to MdToolbar.
 /** @docs-private */
@@ -30,7 +26,6 @@ export class MdToolbarBase {
 }
 export const _MdToolbarMixinBase = mixinColor(MdToolbarBase);
 
-
 @Component({
   moduleId: module.id,
   selector: 'md-toolbar, mat-toolbar',
@@ -44,10 +39,35 @@ export const _MdToolbarMixinBase = mixinColor(MdToolbarBase);
   changeDetection: ChangeDetectionStrategy.OnPush,
   encapsulation: ViewEncapsulation.None
 })
-export class MdToolbar extends _MdToolbarMixinBase implements CanColor {
+export class MdToolbar extends _MdToolbarMixinBase implements CanColor, AfterViewInit {
 
-  constructor(renderer: Renderer2, elementRef: ElementRef) {
+  /** Element reference to the default first row of the toolbar. */
+  @ViewChild('defaultFirstRow', { read: ElementRef }) _defaultFirstRow: ElementRef;
+
+  constructor(renderer: Renderer2, elementRef: ElementRef, private _platform: Platform) {
     super(renderer, elementRef);
   }
 
+  ngAfterViewInit() {
+    // Do nothing if we're not on the browser platform.
+    if (!this._platform.isBrowser) {
+      return;
+    }
+
+    const firstRowElement = this._defaultFirstRow.nativeElement;
+
+    // If the first toolbar row, which will be auto-generated, does not have any projected content,
+    // then the auto-generated first toolbar row should be removed. This gives developers
+    // full control over the first toolbar row (e.g. for use with flex-layout).
+    if (!firstRowElement.innerHTML.trim()) {
+      firstRowElement.parentNode.removeChild(firstRowElement);
+    }
+  }
 }
+
+@Directive({
+  selector: 'md-toolbar-row, mat-toolbar-row',
+  host: {'class': 'mat-toolbar-row'},
+})
+export class MdToolbarRow {}
+