Include the current page's URL as an Extra for Assistant voice searches.

This will be used by Assistant to enable readout of the current page and, eventually, translation. It is only included in Intents initiated via the toolbar button and is gated by the AssistantIntentPageUrl feature, which is disabled by default.

This change also adds an Extra that Assistant will return to indicate what action was taken (e.g. "TRANSCRIPTION", "TRANSLATE", etc). When no such Extra is included, as will be the case for older Assistant versions, search query transcription is assumed.

Design: https://docs.google.com/document/d/1dmsDrpBRn_zfWKCmme0UWaz2I4zB2dNGx5ypVz468tY/edit

Bug: 1140581
Change-Id: Ic5579c5071b376972a1c4c127f797eda5a6a99e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2542852
Commit-Queue: Josh Simmons <[email protected]>
Reviewed-by: Ilya Sherman <[email protected]>
Reviewed-by: Ted Choc <[email protected]>
Reviewed-by: Weilun Shi <[email protected]>
Reviewed-by: Brandon Wylie <[email protected]>
Cr-Commit-Position: refs/heads/master@{#829325}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index c9c3457..2fd37f0 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -3040,6 +3040,10 @@
      flag_descriptions::kVoiceButtonInTopToolbarName,
      flag_descriptions::kVoiceButtonInTopToolbarDescription, kOsAndroid,
      FEATURE_VALUE_TYPE(chrome::android::kVoiceButtonInTopToolbar)},
+    {"assistant-intent-page-url",
+     flag_descriptions::kAssistantIntentPageUrlName,
+     flag_descriptions::kAssistantIntentPageUrlDescription, kOsAndroid,
+     FEATURE_VALUE_TYPE(chrome::android::kAssistantIntentPageUrl)},
     {"share-button-in-top-toolbar",
      flag_descriptions::kShareButtonInTopToolbarName,
      flag_descriptions::kShareButtonInTopToolbarDescription, kOsAndroid,