Deprecating high-conflict accelerators

This CL designs a framework for deprecated accelerators.
In this CL we deprecate the following accelerators:
- Lock Screen: Ctrl+Shift+L --> Search+L
- Task Manager: Shift+Esc --> Search+Esc

The old accelerators are still enabled, but the user is shown a
notification message telling him about the new accelerator.
UMA stats are recorded for both old and new accelerators.
Keyboard overlay has been updated.

BUG=492454,486198,498565,405317,503351
TEST=manually, ash_unittests --gtest_filter=DeprecatedAcceleratorTester.*,
     ash_unittests --gtest_filter=AcceleratorTableTest.CheckDeprecatedAccelerators

Committed: https://crrev.com/c2b81c9fca4abc10cafdc75d2e7b4f15314e2e5b
Cr-Commit-Position: refs/heads/master@{#335410}

Review URL: https://codereview.chromium.org/1177773002

Cr-Commit-Position: refs/heads/master@{#347865}

2 files changed, 6 insertions, 0 deletions

diff --git a/ash/shell/shell_delegate_impl.cc b/ash/shell/shell_delegate_impl.cc
index 4cd2172..735cd0d 100644
--- a/ash/shell/shell_delegate_impl.cc
+++ b/ash/shell/shell_delegate_impl.cc
@@ -24,6 +24,7 @@
 #include "components/user_manager/user_info_impl.h"
 #include "ui/app_list/app_list_view_delegate.h"
 #include "ui/aura/window.h"
+#include "ui/gfx/image/image.h"
 
 namespace ash {
 namespace shell {
@@ -269,5 +270,9 @@ base::string16 ShellDelegateImpl::GetProductName() const {
   return base::string16();
 }
 
+gfx::Image ShellDelegateImpl::GetDeprecatedAcceleratorImage() const {
+  return gfx::Image();
+}
+
 }  // namespace shell
 }  // namespace ash
diff --git a/ash/shell/shell_delegate_impl.h b/ash/shell/shell_delegate_impl.h
index 255401a..6c054c3 100644
--- a/ash/shell/shell_delegate_impl.h
+++ b/ash/shell/shell_delegate_impl.h
@@ -63,6 +63,7 @@ class ShellDelegateImpl : public ash::ShellDelegate {
                                    ash::ShelfItem* item) override;
   GPUSupport* CreateGPUSupport() override;
   base::string16 GetProductName() const override;
+  gfx::Image GetDeprecatedAcceleratorImage() const override;
 
  private:
   // Used to update Launcher. Owned by main.