Add additional keyboard shortcuts for next/prev tab.

Add cmd-{/} keyboard shortcuts to match Mac desktop, in addition to the
commands that are already there. Additionally fix up the directionality
to take RTL into account.

BUG=988313

Change-Id: I9b8b69c30a85f0dbc9e38a5d8a6b72a97355d06f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2427422
Auto-Submit: Mike Pinkerton <pinkerton@chromium.org>
Commit-Queue: Mark Cogan <marq@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810322}

ios/chrome/app/strings/ios_strings.grd

@@ -1015,6 +1015,12 @@ Because your account is managed by <ph name="HOSTED_DOMAIN">$1<ex>google.com</ex
       <message name="IDS_IOS_KEYBOARD_REOPEN_CLOSED_TAB" desc="Title of the keyboard shortcut to reopen a recently closed tab. [Length: 20 em] [iOS only]">
         Reopen Closed Tab
       </message>
+      <message name="IDS_IOS_KEYBOARD_NEXT_TAB" desc="Title of the keyboard shortcut to switch to the next tab in the tab strip. [Length: 20 em] [iOS only]">
+        Next Tab
+      </message>
+      <message name="IDS_IOS_KEYBOARD_PREVIOUS_TAB" desc="Title of the keyboard shortcut to switch to the previous tab in the tab strip. [Length: 20 em] [iOS only]">
+        Previous Tab
+      </message>
       <message name="IDS_IOS_LONG_PRESS_TOOLBAR_IPH_PROMOTION_TEXT" desc="Text for the LongPress Toolbar Tip in-product help promotion, explaining that the user can long press on the toolbar's button to display more options. [iOS only]">
         Touch &amp; hold for more tab options
       </message>

ios/chrome/app/strings/ios_strings_grd/IDS_IOS_KEYBOARD_NEXT_TAB.png.sha1

+ce0e6afda38f6e05303f521b39b9cc4128133723
\ No newline at end of file

ios/chrome/app/strings/ios_strings_grd/IDS_IOS_KEYBOARD_PREVIOUS_TAB.png.sha1

+ce0e6afda38f6e05303f521b39b9cc4128133723
\ No newline at end of file

ios/chrome/browser/ui/browser_view/key_commands_provider.mm

@@ -66,6 +66,25 @@
     };
   }
 
+  // Blocks for next/previous tab.
+  void (^focusTabLeft)();
+  void (^focusTabRight)();
+  if (useRTLLayout) {
+    focusTabLeft = ^{
+      [weakConsumer focusNextTab];
+    };
+    focusTabRight = ^{
+      [weakConsumer focusPreviousTab];
+    };
+  } else {
+    focusTabLeft = ^{
+      [weakConsumer focusPreviousTab];
+    };
+    focusTabRight = ^{
+      [weakConsumer focusNextTab];
+    };
+  }
+
   // New tab blocks.
   void (^newTab)() = ^{
     OpenNewTabCommand* newTabCommand = [OpenNewTabCommand command];
@@ -169,6 +188,44 @@
                                         [weakDispatcher closeCurrentTab];
                                       }
                                     }],
+    ]];
+
+    // Deal with the multiple next/previous tab commands we have, only one pair
+    // of which appears in the HUD. Take RTL into account for the direction.
+    const int tabLeftDescriptionID = useRTLLayout
+                                          ? IDS_IOS_KEYBOARD_NEXT_TAB
+                                          : IDS_IOS_KEYBOARD_PREVIOUS_TAB;
+    const int tabRightDescriptionID = useRTLLayout
+                                           ? IDS_IOS_KEYBOARD_PREVIOUS_TAB
+                                           : IDS_IOS_KEYBOARD_NEXT_TAB;
+    NSString* tabLeftTitle = l10n_util::GetNSStringWithFixup(
+        tabLeftDescriptionID);
+    NSString* tabRightTitle = l10n_util::GetNSStringWithFixup(
+        tabRightDescriptionID);
+    [keyCommands addObjectsFromArray:@[
+      [UIKeyCommand
+           cr_keyCommandWithInput:UIKeyInputLeftArrow
+                    modifierFlags:UIKeyModifierCommand | UIKeyModifierAlternate
+                            title:tabLeftTitle
+                           action:focusTabLeft],
+       [UIKeyCommand
+           cr_keyCommandWithInput:UIKeyInputRightArrow
+                    modifierFlags:UIKeyModifierCommand | UIKeyModifierAlternate
+                            title:tabRightTitle
+                           action:focusTabRight],
+       [UIKeyCommand
+           cr_keyCommandWithInput:@"{"
+                    modifierFlags:UIKeyModifierCommand
+                            title:nil
+                           action:focusTabLeft],
+       [UIKeyCommand
+           cr_keyCommandWithInput:@"}"
+                    modifierFlags:UIKeyModifierCommand
+                            title:nil
+                           action:focusTabRight],
+    ]];
+
+    [keyCommands addObjectsFromArray:@[
       [UIKeyCommand
           cr_keyCommandWithInput:@"d"
                    modifierFlags:UIKeyModifierCommand
@@ -339,20 +396,6 @@
                                     action:^{
                                       focusTab([weakConsumer tabsCount] - 1);
                                     }],
-      [UIKeyCommand
-          cr_keyCommandWithInput:UIKeyInputLeftArrow
-                   modifierFlags:UIKeyModifierCommand | UIKeyModifierAlternate
-                           title:nil
-                          action:^{
-                            [weakConsumer focusPreviousTab];
-                          }],
-      [UIKeyCommand
-          cr_keyCommandWithInput:UIKeyInputRightArrow
-                   modifierFlags:UIKeyModifierCommand | UIKeyModifierAlternate
-                           title:nil
-                          action:^{
-                            [weakConsumer focusNextTab];
-                          }],
       [UIKeyCommand
           cr_keyCommandWithInput:@"\t"
                    modifierFlags:UIKeyModifierControl | UIKeyModifierShift