Corrected dependency for mojo type Clipboard

The header used was not publically reachable via ui/base
so the dependency needs to be a bit more precise.

The exact error message from gn check --check-generated:

ERROR at //out/Default/gen/third_party/blink/public/mojom/clipboard/clipboard.mojom.h:48:11: Can't include this header from here.
- #include "ui/base/clipboard/clipboard_types.h"
          ^----------------------------------
The target:
  //third_party/blink/public/mojom:mojom_platform
is including a file from the target:
  //ui/base/clipboard:clipboard_types

It's usually best to depend directly on the destination target.
In some cases, the destination target is considered a subcomponent
of an intermediate target. In this case, the intermediate target
should depend publicly on the destination to forward the ability
to include headers.

Dependency chain (there may also be others):
  //third_party/blink/public/mojom:mojom_platform -->
  //ui/base:base --[private]-->
  //ui/base/clipboard:clipboard_types

Bug: 938893
Change-Id: Ica45c5a6710f55f5ee4394a1b2c82fd3a6536531
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1547729
Auto-Submit: Daniel Bratell <bratell@opera.com>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#646680}

ui/base/mojo/clipboard.typemap

@@ -5,7 +5,7 @@
 mojom = "//ui/base/mojo/clipboard.mojom"
 public_headers = [ "//ui/base/clipboard/clipboard_types.h" ]
 traits_headers = [ "//ui/base/mojo/clipboard_struct_traits.h" ]
-deps = [
-  "//ui/base",
+public_deps = [
+  "//ui/base/clipboard:clipboard_types",
 ]
 type_mappings = [ "ui.mojom.ClipboardType=ui::ClipboardType" ]

ui/base/mojo/clipboard_blink.typemap

@@ -5,7 +5,7 @@
 mojom = "//third_party/blink/public/mojom/clipboard/clipboard.mojom"
 public_headers = [ "//ui/base/clipboard/clipboard_types.h" ]
 traits_headers = [ "//ui/base/mojo/clipboard_blink_struct_traits.h" ]
-deps = [
-  "//ui/base",
+public_deps = [
+  "//ui/base/clipboard:clipboard_types",
 ]
 type_mappings = [ "blink.mojom.ClipboardBuffer=ui::ClipboardType" ]