[iOS][OpenIn] Refactors OpenIn toolbar

This CL refactors the Open In toolbar and makes the following changes:
- Updates constraints using autoLayout.
- Replaces the MDCButton by an UIButton.
- Button text is no longer in uppercase.
- Cleans unused variables & methods.

based on: https://crrev.com/c/2517483

Bug: 1145477, 1136837, 1117398
Change-Id: I636adc502df159c077f3dc44dbf8d86dc6c0cf97
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2517574
Commit-Queue: Ewann Pellé <ewannpv@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824368}

ios/chrome/browser/ui/open_in/BUILD.gn

@@ -26,7 +26,6 @@ source_set("open_in") {
     "//ios/chrome/browser/web_state_list",
     "//ios/chrome/common/ui/colors",
     "//ios/chrome/common/ui/util",
-    "//ios/third_party/material_components_ios",
     "//ios/web/public",
     "//net",
     "//services/network/public/cpp",

ios/chrome/browser/ui/open_in/open_in_controller.mm

@@ -325,7 +325,6 @@ class OpenInControllerBridge
 
   OpenInToolbar* openInToolbar = [self openInToolbar];
   if (!_isOpenInToolbarDisplayed) {
-    [openInToolbar updateBottomMarginHeight];
     [UIView animateWithDuration:kOpenInToolbarAnimationDuration
                      animations:^{
                        [openInToolbar setAlpha:1.0];

ios/chrome/browser/ui/open_in/open_in_toolbar.h

@@ -9,10 +9,13 @@
 
 @interface OpenInToolbar : UIView
 
-- (instancetype)initWithTarget:(id)target action:(SEL)action;
+// Init with the given local target and action.
+- (instancetype)initWithTarget:(id)target
+                        action:(SEL)action NS_DESIGNATED_INITIALIZER;
 
-// Updates the constraint managing the bottom margin height using NamedGuides.
-- (void)updateBottomMarginHeight;
+- (instancetype)initWithFrame:(CGRect)aRect NS_UNAVAILABLE;
+
+- (instancetype)initWithCoder:(NSCoder*)aDecoder NS_UNAVAILABLE;
 
 @end