Refine the style of the bottom toolbar in iOS history.

As per UI review request, adjust the style of history ClearBrowsingBar:
1. Horizontal margin: 16pt
2. Vertical margin: 8pt
3. Spacing between button: 8pt
4. Font size: (same as bookmark cell)
5. Font color
6. Shadow opacity and radius
7. Button text wraps across multi-lines when needed (and bar height will
   grow when text wrapped.)

Screenshot:
https://drive.google.com/file/d/1rRj-1fKsjRk8n0rG6C-XB2mXoyPooMC6

Bug: 788601
Change-Id: I9a0fbe68122e01301665a48ed77086be96d7de65
Reviewed-on: https://chromium-review.googlesource.com/790013
Commit-Queue: Marti Wong <martiw@chromium.org>
Reviewed-by: Louis Romero <lpromero@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519535}

ios/chrome/browser/ui/history/clear_browsing_bar.h

@@ -30,6 +30,8 @@
 - (void)setDeleteTarget:(id)taret action:(SEL)action;
 // Sets the target/action of the "Cancel" button.
 - (void)setCancelTarget:(id)target action:(SEL)action;
+// Updates the height of the ClearBrowsingBar.
+- (void)updateHeight;
 
 @end
 #endif  // IOS_CHROME_BROWSER_UI_HISTORY_CLEAR_BROWSING_BAR_H_

ios/chrome/browser/ui/history/history_panel_view_controller.mm

@@ -188,6 +188,11 @@ CGFloat kShadowOpacity = 0.2f;
   return NO;
 }
 
+- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)orient {
+  [super didRotateFromInterfaceOrientation:orient];
+  [_clearBrowsingBar updateHeight];
+}
+
 #pragma mark - Status bar
 
 - (BOOL)modalPresentationCapturesStatusBarAppearance {