Centering turn on Bluetooth message on the chooser

Currently the message "Turn on Bluetooth to allow pairing" is aligned
left on the chooser. This CL moves it to the center of the chooser.

I uploaded some screenshots on the issue page.

BUG=664240

Review-Url: https://codereview.chromium.org/2627483003
Cr-Commit-Position: refs/heads/master@{#443015}

chrome/android/java/res/layout/item_chooser_dialog.xml

@@ -22,23 +22,25 @@
         android:paddingEnd="16dp"
         android:textSize="16sp" />
 
-    <!-- The "no item found" message. -->
-    <org.chromium.ui.widget.TextViewWithClickableSpans
-        android:id="@+id/not_found_message"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_marginTop="8dp"
-        android:layout_marginStart="16dp"
-        android:layout_marginEnd="16dp"
-        android:textSize="16sp"
-        android:visibility="gone" />
-
     <!-- A layout containing a spinning progress bar that gets replaced with a
          list of items. -->
     <FrameLayout
         android:id="@+id/container"
         android:layout_width="fill_parent"
         android:layout_height="100dp" >
+
+        <!-- The "no item found" message. -->
+        <org.chromium.ui.widget.TextViewWithClickableSpans
+            android:id="@+id/not_found_message"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center"
+            android:layout_marginTop="8dp"
+            android:layout_marginStart="16dp"
+            android:layout_marginEnd="16dp"
+            android:textSize="16sp"
+            android:visibility="gone" />
+
         <ProgressBar
             android:id="@+id/progress"
             android:layout_width="24dp"

chrome/browser/ui/cocoa/device_chooser_content_view_cocoa.mm

@@ -5,6 +5,7 @@
 #import "chrome/browser/ui/cocoa/device_chooser_content_view_cocoa.h"
 
 #include <algorithm>
+#include <cmath>
 
 #include "base/macros.h"
 #include "base/strings/sys_string_conversions.h"
@@ -60,9 +61,6 @@ const CGFloat kSeparatorHeight = 1.0f;
 const CGFloat kTableRowViewHorizontalPadding = 5.0f;
 const CGFloat kTableRowViewVerticalPadding = 1.0f;
 
-// Distance between the adapter off help link and the scroll view boundaries.
-const CGFloat kAdapterOffHelpLinkPadding = 5.0f;
-
 // The lookup table for signal strength level image.
 const int kSignalStrengthLevelImageIds[5] = {IDR_SIGNAL_0_BAR, IDR_SIGNAL_1_BAR,
                                              IDR_SIGNAL_2_BAR, IDR_SIGNAL_3_BAR,
@@ -434,6 +432,7 @@ void ChooserContentViewController::UpdateTableView() {
     // Adapter turned off message.
     adapterOffMessage_ = CreateLabel(l10n_util::GetNSStringF(
         IDS_BLUETOOTH_DEVICE_CHOOSER_TURN_ADAPTER_OFF, base::string16()));
+    CGFloat adapterOffMessageWidth = NSWidth([adapterOffMessage_ frame]);
 
     // Connect button.
     connectButton_ = [self createConnectButton];
@@ -528,10 +527,13 @@ void ChooserContentViewController::UpdateTableView() {
     [self addSubview:titleView_];
 
     // Adapter turned off help button.
-    CGFloat adapterOffHelpButtonOriginX = kMarginX + kAdapterOffHelpLinkPadding;
-    CGFloat adapterOffHelpButtonOriginY = titleOriginY - kVerticalPadding -
-                                          adapterOffHelpButtonHeight -
-                                          kAdapterOffHelpLinkPadding;
+    CGFloat adapterOffHelpButtonOriginX = std::floor(
+        scrollViewOriginX +
+        (scrollViewWidth - adapterOffHelpButtonWidth - adapterOffMessageWidth) /
+            2);
+    CGFloat adapterOffHelpButtonOriginY =
+        std::floor(scrollViewOriginY +
+                   (scrollViewHeight - adapterOffHelpButtonHeight) / 2);
     [adapterOffHelpButton_
         setFrameOrigin:NSMakePoint(adapterOffHelpButtonOriginX,
                                    adapterOffHelpButtonOriginY)];

chrome/browser/ui/views/device_chooser_content_view.cc

@@ -106,8 +106,13 @@ void DeviceChooserContentView::Layout() {
   throbber_->SetBounds((rect.width() - kThrobberDiameter) / 2,
                        (rect.height() - kThrobberDiameter) / 2,
                        kThrobberDiameter, kThrobberDiameter);
+  // Set the adapter off message in the center of the chooser.
+  // The adapter off message will only be shown when the adapter is off,
+  // and in that case, the system won't be able to scan for devices, so
+  // the throbber won't be shown at the same time.
   turn_adapter_off_help_->SetPosition(
-      gfx::Point(kAdapterOffHelpLinkPadding, kAdapterOffHelpLinkPadding));
+      gfx::Point((rect.width() - turn_adapter_off_help_->width()) / 2,
+                 (rect.height() - turn_adapter_off_help_->height()) / 2));
   turn_adapter_off_help_->SizeToFit(rect.width() -
                                     2 * kAdapterOffHelpLinkPadding);
   views::View::Layout();