Register Assistant key as a supported accelerator in autotest API.

This CL adds Assistant key to the supported accelerator list used
in AutotestPrivateActivateAcceleratorFunction, so that we can mimic
the key press to open/close the Assistant UI in the integration test
through that API.

Related CL using this API:
https://chromium-review.googlesource.com/c/chromiumos/platform/tast-tests/+/1975040

Misc: fixes Linter warnings.

Bug: b/145218971
Test: local compile.
Change-Id: Icafcaea356e55319ff7ccf4300a2b6a2ee697d7d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1977192
Commit-Queue: Meilin Wang <meilinw@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726630}

chrome/browser/chromeos/extensions/autotest_private/autotest_private_api.cc

@@ -4,6 +4,8 @@
 
 #include "chrome/browser/chromeos/extensions/autotest_private/autotest_private_api.h"
 
+#include <algorithm>
+#include <deque>
 #include <set>
 #include <sstream>
 #include <utility>
@@ -569,6 +571,7 @@ ui::KeyboardCode StringToKeyCode(const std::string& str) {
     ui::KeyboardCode key_code;
   } map[] = {
       {"search", ui::VKEY_LWIN},
+      {"assistant", ui::VKEY_ASSISTANT},
   };
   DCHECK(base::IsStringASCII(str));
   if (str.length() == 1) {
@@ -3789,7 +3792,7 @@ ExtensionFunction::ResponseAction AutotestPrivateMouseMoveFunction::Run() {
   int flags = env->mouse_button_flags();
   ui::EventType type = (flags == 0) ? ui::ET_MOUSE_MOVED : ui::ET_MOUSE_DRAGGED;
   for (int64_t i = 1; i <= steps; ++i) {
-    double progress = double(i) / double(steps);
+    double progress = static_cast<double>(i) / static_cast<double>(steps);
     gfx::PointF point(gfx::Tween::FloatValueBetween(progress, start_in_host.x(),
                                                     location_in_host.x()),
                       gfx::Tween::FloatValueBetween(progress, start_in_host.y(),