Extensions: Fix missing images and cleanup flattenhtml usage.

flattenhtml does not work with Polymer3 generated files. Instead register
images with the WebUIDataSource so that they can be served by a
chrome://extensions URL.

Bug: None
Change-Id: I33346fac61b1f4d0937615fa8dde38c22809de89
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2003196Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732542}

chrome/browser/resources/extensions/extensions_resources.grd

@@ -41,7 +41,7 @@
                use_base_dir="false" type ="BINDATA" />
       <include name="IDR_EXTENSIONS_ERROR_PAGE_JS"
                file="${root_gen_dir}/chrome/browser/resources/extensions/error_page.js"
-               use_base_dir="false" type ="BINDATA" flattenhtml="true" />
+               use_base_dir="false" type ="BINDATA" />
       <include name="IDR_EXTENSIONS_KEYBOARD_SHORTCUTS_JS"
                file="${root_gen_dir}/chrome/browser/resources/extensions/keyboard_shortcuts.js"
                use_base_dir="false" type ="BINDATA" />
@@ -52,7 +52,7 @@
     </if>
       <include name="IDR_EXTENSIONS_MANAGER_JS"
                file="${root_gen_dir}/chrome/browser/resources/extensions/manager.js"
-               use_base_dir="false" type ="BINDATA" flattenhtml="true" />
+               preprocess="true" use_base_dir="false" type ="BINDATA" />
       <include name="IDR_EXTENSIONS_ICONS_JS"
                file="${root_gen_dir}/chrome/browser/resources/extensions/icons.js"
                use_base_dir="false" type ="BINDATA" />
@@ -103,12 +103,11 @@
                use_base_dir="false" type ="BINDATA" />
       <include name="IDR_EXTENSIONS_TOOLBAR_JS"
                file="${root_gen_dir}/chrome/browser/resources/extensions/toolbar.js"
-               use_base_dir="false" type ="BINDATA" flattenhtml="true" />
-      <include name="IDR_WEBUI_IMAGES_CHECKUP_IMAGE"
-               file="checkup_image.svg" type="BINDATA" compress="gzip" />
-      <include name="IDR_WEBUI_IMAGES_CHECKUP_IMAGE_DARKMODE"
-               file="checkup_image_dark.svg" type="BINDATA"
-               compress="gzip" />
+               preprocess="true" use_base_dir="false" type ="BINDATA" />
+      <include name="IDR_EXTENSIONS_CHECKUP_IMAGE"
+               file="checkup_image.svg" type="BINDATA" />
+      <include name="IDR_EXTENSIONS_CHECKUP_IMAGE_DARK"
+               file="checkup_image_dark.svg" type="BINDATA" />
     </includes>
     <structures>
       <structure name="IDR_EXTENSIONS_ITEM_BEHAVIOR_JS"

chrome/browser/resources/extensions/extensions_resources_vulcanized.grd

@@ -22,6 +22,14 @@
                preprocess="true"
                type="BINDATA"
                compress="gzip" />
+      <include name="IDR_EXTENSIONS_CHECKUP_IMAGE"
+               file="checkup_image.svg"
+               type="BINDATA"
+               compress="gzip" />
+      <include name="IDR_EXTENSIONS_CHECKUP_IMAGE_DARK"
+               file="checkup_image_dark.svg"
+               type="BINDATA"
+               compress="gzip" />
     </includes>
   </release>
 </grit>

chrome/browser/ui/webui/extensions/extensions_ui.cc

@@ -73,6 +73,9 @@ content::WebUIDataSource* CreateMdExtensionsSource(Profile* profile,
   webui::SetupBundledWebUIDataSource(source, "extensions.js",
                                      IDR_EXTENSIONS_EXTENSIONS_ROLLUP_JS,
                                      IDR_EXTENSIONS_EXTENSIONS_HTML);
+  source->AddResourcePath("checkup_image.svg", IDR_EXTENSIONS_CHECKUP_IMAGE);
+  source->AddResourcePath("checkup_image_dark.svg",
+                          IDR_EXTENSIONS_CHECKUP_IMAGE_DARK);
 #else
   webui::SetupWebUIDataSource(
       source, base::make_span(kExtensionsResources, kExtensionsResourcesSize),