Give AphrontTagView a getViewer(), deprecate getUser()

Summary:
Two minor changes here:

  - Replace `get/setUser()` with `get/setViewer()` for consistency with everything else.
  - `getViewer()` now throws if no viewer is set. We had a lot of code that either "should" check this but didn't, or did check it in an identical way, duplicating work. In contrast, very little code checks for a viewer but works if one is not present.

Test Plan:
  - Grepped for `->user`.
  - Attempted to fix all callsites inside `*View` classes.
  - Browsed around a bunch of applications, particularly Calendar, Differential and Diffusion, which seemed most heavily affected.

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D15412

src/applications/phame/view/PhameBlogListView.php

@@ -3,7 +3,6 @@
 final class PhameBlogListView extends AphrontTagView {
 
   private $blogs;
-  private $viewer;
 
   public function setBlogs($blogs) {
     assert_instances_of($blogs, 'PhameBlog');
@@ -11,11 +10,6 @@ final class PhameBlogListView extends AphrontTagView {
     return $this;
   }
 
-  public function setViewer($viewer) {
-    $this->viewer = $viewer;
-    return $this;
-  }
-
   protected function getTagAttributes() {
     $classes = array();
     $classes[] = 'phame-blog-list';

src/applications/phame/view/PhameDraftListView.php

@@ -4,7 +4,6 @@ final class PhameDraftListView extends AphrontTagView {
 
   private $posts;
   private $blogs;
-  private $viewer;
 
   public function setPosts($posts) {
     assert_instances_of($posts, 'PhamePost');
@@ -18,11 +17,6 @@ final class PhameDraftListView extends AphrontTagView {
     return $this;
   }
 
-  public function setViewer($viewer) {
-    $this->viewer = $viewer;
-    return $this;
-  }
-
   protected function getTagAttributes() {
     $classes = array();
     $classes[] = 'phame-blog-list';

src/applications/phame/view/PhamePostListView.php

@@ -4,7 +4,6 @@ final class PhamePostListView extends AphrontTagView {
 
   private $posts;
   private $nodata;
-  private $viewer;
   private $showBlog = false;
   private $isExternal;
   private $isLive;
@@ -25,11 +24,6 @@ final class PhamePostListView extends AphrontTagView {
     return $this;
   }
 
-  public function setViewer($viewer) {
-    $this->viewer = $viewer;
-    return $this;
-  }
-
   public function setIsExternal($is_external) {
     $this->isExternal = $is_external;
     return $this;
@@ -53,7 +47,7 @@ final class PhamePostListView extends AphrontTagView {
   }
 
   protected function getTagContent() {
-    $viewer = $this->viewer;
+    $viewer = $this->getViewer();
     $posts = $this->posts;
     $nodata = $this->nodata;