[unseasoned-pdf] Fix PDFExtensionJSText.BasicPlugin

Focuses the frame containing the plugin before trying to change the text
selection. This avoids a DCHECK when changing the text selection on that
frame, but the OnTextSelectionChanged() event subsequently gets sent to
the MimeHandlerView's frame, which isn't ready for it.

Fixed: 1229631
Change-Id: Ief54f4337271591d41313acd11b695f20c89daa2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3061429
Auto-Submit: K. Moon <kmoon@chromium.org>
Commit-Queue: Hui Yingst <nigi@chromium.org>
Reviewed-by: Hui Yingst <nigi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#906945}

chrome/browser/pdf/pdf_extension_test.cc

@@ -912,8 +912,7 @@ IN_PROC_BROWSER_TEST_P(PDFExtensionJSTest, Basic) {
   EXPECT_EQ(1, CountPDFProcesses());
 }
 
-IN_PROC_BROWSER_TEST_F(PDFExtensionJSTestWithoutUnseasonedOverride,
-                       BasicPlugin) {
+IN_PROC_BROWSER_TEST_P(PDFExtensionJSTest, BasicPlugin) {
   RunTestsInJsModule("basic_plugin_test.js", "test.pdf");
 }
 

pdf/pdf_view_web_plugin.cc

@@ -60,6 +60,7 @@
 #include "third_party/blink/public/web/web_plugin_container.h"
 #include "third_party/blink/public/web/web_plugin_params.h"
 #include "third_party/blink/public/web/web_print_preset_options.h"
+#include "third_party/blink/public/web/web_view.h"
 #include "third_party/blink/public/web/web_widget.h"
 #include "third_party/skia/include/core/SkRect.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
@@ -177,7 +178,14 @@ class BlinkContainerWrapper final : public PdfViewWebPlugin::ContainerWrapper {
   void TextSelectionChanged(const blink::WebString& selection_text,
                             uint32_t offset,
                             const gfx::Range& range) override {
-    GetFrame()->TextSelectionChanged(selection_text, offset, range);
+    // Focus the plugin's containing frame before changing the text selection.
+    // TODO(crbug.com/1234559): Would it make more sense not to change the text
+    // selection at all in this case? Maybe we only have this problem because we
+    // support a "selectAll" message.
+    blink::WebLocalFrame* frame = GetFrame();
+    frame->View()->SetFocusedFrame(frame);
+
+    frame->TextSelectionChanged(selection_text, offset, range);
   }
 
   std::unique_ptr<blink::WebAssociatedURLLoader> CreateAssociatedURLLoader(