capture_mode: Record metric for ctrl + overview accelerator.

Currently ctrl + overview calls
CaptureModeController::CaptureScreenshotsOfALlDisplays() but this does
not record any metrics.

This CL changes it so when CaptureScreenshotsOfALlDisplays() is called,
it records to Ash.CaptureModeController.EntryPoint and
Ash.CaptureModeController.CaptureConfiguration.

Test: manual
Bug: 1140182
Change-Id: I0671ba00ef2ddb8b75c502f8495ed6259b78a1b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2637778Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: Jeremy Chinsen <chinsenj@chromium.org>
Commit-Queue: Jeremy Chinsen <chinsenj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845198}

ash/capture_mode/capture_mode_controller.cc

@@ -421,6 +421,11 @@ void CaptureModeController::CaptureScreenshotsOfAllDisplays() {
                                      : BuildImagePathForDisplay(display_index));
     ++display_index;
   }
+
+  // Since this doesn't create a capture mode session, log metrics here.
+  RecordCaptureModeEntryType(CaptureModeEntryType::kCaptureAllDisplays);
+  RecordCaptureModeConfiguration(CaptureModeType::kImage,
+                                 CaptureModeSource::kFullscreen);
 }
 
 void CaptureModeController::PerformCapture() {

ash/capture_mode/capture_mode_metrics.h

@@ -65,7 +65,8 @@ enum class CaptureModeEntryType {
   kStylusPalette,
   kPowerMenu,
   kSnipKey,
-  kMaxValue = kSnipKey,
+  kCaptureAllDisplays,
+  kMaxValue = kCaptureAllDisplays,
 };
 
 // Enumeration of quick actions on screenshot notification. Note that these

tools/metrics/histograms/enums.xml

@@ -9549,6 +9549,7 @@ Called by update_bad_message_reasons.py.-->
   <int value="3" label="Stylus Palette"/>
   <int value="4" label="Power Menu"/>
   <int value="5" label="Snip Key"/>
+  <int value="6" label="Full Screenshot Accelerator"/>
 </enum>
 
 <enum name="CapturePixelFormat">