[Omnibox] Implement ClipboardRecentContentGeneric::GetRecentTextFromClipboard

For enabling "Text you copied" on Clank, we need this function to provide
Text in Android's clipboard.

Bug:989143

Change-Id: I35032a6468f3bbae87b0027caa3924aa8af070b5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1726276Reviewed-by: Cait Phillips <caitkp@chromium.org>
Reviewed-by: Ender <ender@google.com>
Commit-Queue: Gang Wu <gangwu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683766}

components/open_from_clipboard/clipboard_recent_content_generic.cc

@@ -65,7 +65,19 @@ ClipboardRecentContentGeneric::GetRecentURLFromClipboard() {
 
 base::Optional<base::string16>
 ClipboardRecentContentGeneric::GetRecentTextFromClipboard() {
-  return base::nullopt;
+  if (GetClipboardContentAge() > MaximumAgeOfClipboard())
+    return base::nullopt;
+
+  base::string16 text_from_clipboard;
+  ui::Clipboard::GetForCurrentThread()->ReadText(ui::ClipboardType::kCopyPaste,
+                                                 &text_from_clipboard);
+  base::TrimWhitespace(text_from_clipboard, base::TrimPositions::TRIM_ALL,
+                       &text_from_clipboard);
+  if (text_from_clipboard.empty()) {
+    return base::nullopt;
+  }
+
+  return text_from_clipboard;
 }
 
 base::Optional<gfx::Image>

components/open_from_clipboard/clipboard_recent_content_generic_unittest.cc

@@ -9,6 +9,7 @@
 
 #include "base/stl_util.h"
 #include "base/strings/string16.h"
+#include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/base/clipboard/test/test_clipboard.h"
@@ -118,3 +119,17 @@ TEST_F(ClipboardRecentContentGenericTest, SuppressClipboardContent) {
   test_clipboard_->SetLastModifiedTime(now);
   EXPECT_TRUE(recent_content.GetRecentURLFromClipboard().has_value());
 }
+
+TEST_F(ClipboardRecentContentGenericTest, GetRecentTextFromClipboard) {
+  // Make sure the Text is suggested.
+  ClipboardRecentContentGeneric recent_content;
+  base::Time now = base::Time::Now();
+  std::string text = "  Foo Bar   ";
+  test_clipboard_->WriteText(text.data(), text.length());
+  test_clipboard_->SetLastModifiedTime(now - base::TimeDelta::FromSeconds(10));
+  EXPECT_TRUE(recent_content.GetRecentTextFromClipboard().has_value());
+  EXPECT_STREQ(
+      "Foo Bar",
+      base::UTF16ToUTF8(recent_content.GetRecentTextFromClipboard().value())
+          .c_str());
+}