[ios] Fix layout issues when starting phone in voice call.

UIKit seems to be insetting our root view controller by 20 points when
in a phone call, but setting our main_view_controller to
self.window.bounds is stomping on that. It's seems that pre-iOS11
this inset would still happen later.  This issue appears when compiling
against the iOS11 SDK, even when running on iOS10 or iOS9 devices, it
seems.

[email protected]

(cherry picked from commit 13b7c43)

Bug: 755974
Change-Id: I25b6e3848ae506b5531b5eb28348ac5328a6c779
Reviewed-on: https://chromium-review.googlesource.com/668046
Reviewed-by: Rohit Rao (ping after 24h) <[email protected]>
Reviewed-by: Mark Cogan <[email protected]>
Commit-Queue: Justin Cohen <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#502230}
Reviewed-on: https://chromium-review.googlesource.com/673423
Reviewed-by: Justin Cohen <[email protected]>
Cr-Commit-Position: refs/branch-heads/3202@{crosswalk-project#324}
Cr-Branched-From: fa6a5d8-refs/heads/master@{#499098}

ios/chrome/browser/ui/browser_view_controller.mm

@@ -1223,7 +1223,7 @@ - (void)presentBubblesIfEligible {
 
 // Perform additional set up after loading the view, typically from a nib.
 - (void)viewDidLoad {
-  CGRect initialViewsRect = self.view.frame;
+  CGRect initialViewsRect = self.view.bounds;
   initialViewsRect.origin.y += StatusBarHeight();
   initialViewsRect.size.height -= StatusBarHeight();
   UIViewAutoresizing initialViewAutoresizing =

ios/chrome/browser/ui/main/main_coordinator.mm

@@ -32,9 +32,6 @@ - (void)start {
   MainViewController* mainViewController = [[MainViewController alloc] init];
   _mainViewController = mainViewController;
   self.window.rootViewController = self.mainViewController;
-
-  // Size the main view controller to fit the whole screen.
-  [self.mainViewController.view setFrame:self.window.bounds];
 }
 
 @end