[iOS] Support keyboard commands in pre-edit.

Allows using Cmd+C/Cmd+V/Cmd+X when the textfield is in pre-edit state.
Allows using arrow-left and arrow-right keys to go to the start/end of
the string and exit pre-edit, like on desktop.

Bug: 136291
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Ibe71f4d2b6adba3df310051edf4ffa42832217c2
Reviewed-on: https://chromium-review.googlesource.com/951783
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543341}

ios/chrome/browser/ui/omnibox/omnibox_text_field_ios.mm

@@ -628,6 +628,13 @@ NSString* const kOmniboxFadeAnimationKey = @"OmniboxFadeAnimation";
     return NO;
   }
 
+  if ([self isPreEditing]) {
+    // Allow cut/copy/paste in preedit.
+    if ((action == @selector(copy:)) || (action == @selector(cut:))) {
+      return YES;
+    }
+  }
+
   return [super canPerformAction:action withSender:sender];
 }
 
@@ -649,6 +656,17 @@ NSString* const kOmniboxFadeAnimationKey = @"OmniboxFadeAnimation";
     [super copy:sender];
 }
 
+- (void)cut:(id)sender {
+  if ([self isPreEditing]) {
+    [self copy:sender];
+    [self exitPreEditState];
+    NSAttributedString* emptyString = [[NSAttributedString alloc] init];
+    [self setText:emptyString userTextLength:0];
+  } else {
+    [super cut:sender];
+  }
+}
+
 // Overridden to notify the delegate that a paste is in progress.
 - (void)paste:(id)sender {
   id delegate = [self delegate];
@@ -668,7 +686,7 @@ NSString* const kOmniboxFadeAnimationKey = @"OmniboxFadeAnimation";
 
 #pragma mark Key Commands
 
-- (NSArray<UIKeyCommand*>*)keyCommands {
+- (NSArray<UIKeyCommand*>*)upDownCommands {
   // These up/down arrow key commands override the standard UITextInput handling
   // of up/down arrow key. The standard behavior is to go to the beginning/end
   // of the text. Instead, the omnibox popup needs to highlight suggestions.
@@ -684,6 +702,15 @@ NSString* const kOmniboxFadeAnimationKey = @"OmniboxFadeAnimation";
   return @[ commandUp, commandDown ];
 }
 
+- (NSArray<UIKeyCommand*>*)keyCommands {
+  NSMutableArray<UIKeyCommand*>* commands = [[self upDownCommands] mutableCopy];
+  if ([self isPreEditing]) {
+    [commands addObjectsFromArray:[self leftRightCommands]];
+  }
+
+  return commands;
+}
+
 - (void)keyCommandUp {
   [self.suggestionCommandsEndpoint highlightNextSuggestion];
 }
@@ -692,6 +719,40 @@ NSString* const kOmniboxFadeAnimationKey = @"OmniboxFadeAnimation";
   [self.suggestionCommandsEndpoint highlightPreviousSuggestion];
 }
 
+#pragma mark preedit-only key commands
+
+// React to left and right keys when in preedit state to exit preedit and put
+// cursor to the beginning/end of the textfield.
+- (NSArray<UIKeyCommand*>*)leftRightCommands {
+  UIKeyCommand* commandLeft =
+      [UIKeyCommand keyCommandWithInput:UIKeyInputLeftArrow
+                          modifierFlags:0
+                                 action:@selector(keyCommandLeft)];
+  UIKeyCommand* commandRight =
+      [UIKeyCommand keyCommandWithInput:UIKeyInputRightArrow
+                          modifierFlags:0
+                                 action:@selector(keyCommandRight)];
+
+  return @[ commandLeft, commandRight ];
+}
+
+- (void)keyCommandLeft {
+  [self exitPreEditState];
+  UITextPosition* beginning = self.beginningOfDocument;
+  UITextRange* textRange =
+      [self textRangeFromPosition:beginning toPosition:beginning];
+
+  self.selectedTextRange = textRange;
+}
+
+- (void)keyCommandRight {
+  [self exitPreEditState];
+  UITextPosition* end = self.endOfDocument;
+  UITextRange* textRange = [self textRangeFromPosition:end toPosition:end];
+
+  self.selectedTextRange = textRange;
+}
+
 #pragma mark - helpers
 
 // Gets the bounds of the rect covering the URL.

ios/chrome/browser/ui/omnibox/omnibox_view_ios.mm

@@ -609,24 +609,31 @@ void OmniboxViewIOS::OnClear() {
 
 bool OmniboxViewIOS::OnCopy() {
   UIPasteboard* board = [UIPasteboard generalPasteboard];
-  UITextRange* selected_range = [field_ selectedTextRange];
-  base::string16 text =
-      base::SysNSStringToUTF16([field_ textInRange:selected_range]);
-
-  UITextPosition* start = [field_ beginningOfDocument];
-  UITextPosition* end = [field_ endOfDocument];
-  BOOL is_select_all = ([field_ comparePosition:[selected_range start]
-                                     toPosition:start] == NSOrderedSame) &&
-                       ([field_ comparePosition:[selected_range end]
-                                     toPosition:end] == NSOrderedSame);
-
-  // The following call to |-offsetFromPosition:toPosition:| gives the offset in
-  // terms of the number of "visible characters."  The documentation does not
-  // specify whether this means glyphs or UTF16 chars.  This does not matter for
-  // the current implementation of AdjustTextForCopy(), but it may become an
-  // issue at some point.
-  NSInteger start_location =
-      [field_ offsetFromPosition:start toPosition:[selected_range start]];
+  NSString* selectedText = nil;
+  BOOL is_select_all = NO;
+  NSInteger start_location = 0;
+  if ([field_ isPreEditing]) {
+    selectedText = [field_ preEditText];
+    is_select_all = YES;
+    start_location = 0;
+  } else {
+    UITextRange* selected_range = [field_ selectedTextRange];
+    selectedText = [field_ textInRange:selected_range];
+    UITextPosition* start = [field_ beginningOfDocument];
+    UITextPosition* end = [field_ endOfDocument];
+    is_select_all = ([field_ comparePosition:[selected_range start]
+                                  toPosition:start] == NSOrderedSame) &&
+                    ([field_ comparePosition:[selected_range end]
+                                  toPosition:end] == NSOrderedSame);
+    // The following call to |-offsetFromPosition:toPosition:| gives the offset
+    // in terms of the number of "visible characters."  The documentation does
+    // not specify whether this means glyphs or UTF16 chars.  This does not
+    // matter for the current implementation of AdjustTextForCopy(), but it may
+    // become an issue at some point.
+    start_location =
+        [field_ offsetFromPosition:start toPosition:[selected_range start]];
+  }
+  base::string16 text = base::SysNSStringToUTF16(selectedText);
 
   GURL url;
   bool write_url = false;