Avoid sync IPCs for firstRectForCharacterRange/attributedSubstringForProposedRange.

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 66f1c31650f7799701f8aba763b515e7c340aaeb..aeb9db2d4d6d275c32bbe07520d582346a2f3c98 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -1225,6 +1225,7 @@ void RenderWidgetHostViewMac::SelectionBoundsChanged(
     const ViewHostMsg_SelectionBounds_Params& params) {
   if (params.anchor_rect == params.focus_rect)
     caret_rect_ = params.anchor_rect;
+  first_selection_rect_ = params.anchor_rect;
 }
 
 void RenderWidgetHostViewMac::SetShowingContextMenu(bool showing) {
@@ -1453,6 +1454,12 @@ bool RenderWidgetHostViewMac::GetCachedFirstRectForCharacterRange(
     return true;
   }
 
+  if (composition_range_.is_empty()) {
+    *actual_range = selection_range_.ToNSRange();
+    *rect = NSRectFromCGRect(first_selection_rect_.ToCGRect());
+    return true;
+  }
+
   const gfx::Range request_range_in_composition =
       ConvertCharacterRangeToCompositionRange(gfx::Range(range));
   if (request_range_in_composition == gfx::Range::InvalidRange())
@@ -2887,10 +2894,34 @@ extern NSString *NSTextInputReplacementRangeAttributeName;
   // TODO(thakis): Pipe |actualRange| through TextInputClientMac machinery.
   if (actualRange)
     *actualRange = range;
-  NSAttributedString* str =
-      TextInputClientMac::GetInstance()->GetAttributedSubstringFromRange(
-          renderWidgetHostView_->render_widget_host_, range);
-  return str;
+
+  const gfx::Range requested_range(range);
+  if (requested_range.is_reversed())
+    return nil;
+
+  gfx::Range expected_range;
+  const base::string16* expected_text;
+
+  if (!renderWidgetHostView_->composition_range().is_empty()) {
+    expected_text = &markedText_;
+    expected_range = renderWidgetHostView_->composition_range();
+  } else {
+    expected_text = &(renderWidgetHostView_->selection_text());

[Alexei Svitkine (slow), 2015/08/26 15:09:22]

Nit: I'm not sure the parentheses are necessary.

[Shu Chen, 2015/08/26 15:21:02]

Done.

+    size_t offset = renderWidgetHostView_->selection_text_offset();
+    expected_range = gfx::Range(offset, offset + expected_text->size());
+  }
+
+  if (!expected_range.Contains(requested_range))
+    return nil;
+
+  const base::char16* bytes =

[Alexei Svitkine (slow), 2015/08/26 15:09:22]

Nit: Add a comment about why we're doing things this way (i.e. to avoid copies)
above this.

[Shu Chen, 2015/08/26 15:21:02]

Done.

+      &(*expected_text)[requested_range.start() - expected_range.start()];
+  NSUInteger bytes_len = requested_range.length() * sizeof(base::char16);
+  base::scoped_nsobject<NSString> ns_string(
+      [[NSString alloc] initWithBytes:bytes
+                        length:bytes_len

[Alexei Svitkine (slow), 2015/08/26 15:09:22]

Nit: Align :'s

[Shu Chen, 2015/08/26 15:21:02]

Done.

+                        encoding:NSUTF16StringEncoding]);
+  return [[[NSAttributedString alloc] initWithString:ns_string] autorelease];
 }
 
 - (NSInteger)conversationIdentifier {