Image Capture: add a feature flag to ease debugging on the field

This CL adds a feature flag for image capture to ease debugging of
issues in the wild (e.g. https://crbug.com/722038 and
https://crbug.com/709819).  The flag is enabled by default:
  chrome://flags/#enable-image-capture-api

Bug: 735661
Change-Id: Iab06dbc9e6d4a5ecbbf85f70ad7221770915b464
Reviewed-on: https://chromium-review.googlesource.com/544185Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Christian Fremerey <chfremer@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#481924}

chrome/browser/about_flags.cc

@@ -2210,6 +2210,9 @@ const FeatureEntry kFeatureEntries[] = {
     {"enable-webusb", flag_descriptions::kEnableWebUsbName,
      flag_descriptions::kEnableWebUsbDescription, kOsAll,
      FEATURE_VALUE_TYPE(features::kWebUsb)},
+    {"enable-image-capture-api", flag_descriptions::kEnableImageCaptureAPIName,
+     flag_descriptions::kEnableImageCaptureAPIDescription, kOsAll,
+     FEATURE_VALUE_TYPE(features::kImageCaptureAPI)},
 #if defined(OS_ANDROID)
     {"force-show-update-menu-item", flag_descriptions::kUpdateMenuItemName,
      flag_descriptions::kUpdateMenuItemDescription, kOsAndroid,

chrome/browser/flag_descriptions.cc

@@ -2520,6 +2520,12 @@ const char kEnableWebUsbName[] = "WebUSB";
 
 const char kEnableWebUsbDescription[] = "Enable WebUSB support.";
 
+const char kEnableImageCaptureAPIName[] = "Image Capture API";
+
+const char kEnableImageCaptureAPIDescription[] =
+    "Enables the Web Platform Image Capture API: takePhoto(), "
+    "getPhotoCapabilities(), etc.";
+
 const char kEnableGenericSensorName[] = "Generic Sensor";
 
 const char kEnableGenericSensorDescription[] =

chrome/browser/flag_descriptions.h

@@ -266,6 +266,9 @@ extern const char kEnableWasmDescription[];
 extern const char kEnableWebUsbName[];
 extern const char kEnableWebUsbDescription[];
 
+extern const char kEnableImageCaptureAPIName[];
+extern const char kEnableImageCaptureAPIDescription[];
+
 extern const char kEnableZeroSuggestRedirectToChromeName[];
 extern const char kEnableZeroSuggestRedirectToChromeDescription[];
 

chrome/common/chrome_switches.cc

@@ -182,7 +182,7 @@ const char kDisableBackgroundNetworking[]   = "disable-background-networking";
 // Disables the bundled PPAPI version of Flash.
 const char kDisableBundledPpapiFlash[]      = "disable-bundled-ppapi-flash";
 
-// Disable hardware encoding support for Cast Streaming.
+// Disables hardware encoding support for Cast Streaming.
 const char kDisableCastStreamingHWEncoding[] =
     "disable-cast-streaming-hw-encoding";
 

content/browser/image_capture/image_capture_impl.cc

@@ -13,6 +13,7 @@
 #include "content/browser/renderer_host/media/video_capture_manager.h"
 #include "content/common/media/media_stream_options.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/common/content_features.h"
 #include "media/base/bind_to_current_loop.h"
 #include "media/capture/video/video_capture_device.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
@@ -130,6 +131,9 @@ ImageCaptureImpl::~ImageCaptureImpl() {}
 void ImageCaptureImpl::Create(
     const service_manager::BindSourceInfo& source_info,
     media::mojom::ImageCaptureRequest request) {
+  if (!base::FeatureList::IsEnabled(features::kImageCaptureAPI))
+    return;
+
   mojo::MakeStrongBinding(base::MakeUnique<ImageCaptureImpl>(),
                           std::move(request));
 }

content/public/common/content_features.cc

@@ -346,6 +346,10 @@ const base::Feature kWebRtcUseEchoCanceller3{"WebRtcUseEchoCanceller3",
 // https://wicg.github.io/webusb
 const base::Feature kWebUsb{"WebUSB", base::FEATURE_ENABLED_BY_DEFAULT};
 
+// Enables/disables the Image Capture API.
+const base::Feature kImageCaptureAPI{"ImageCaptureAPI",
+                                     base::FEATURE_ENABLED_BY_DEFAULT};
+
 // Enables WebVR experimental rendering optimizations.
 const base::Feature kWebVRExperimentalRendering{
     "WebVRExperimentalRendering", base::FEATURE_DISABLED_BY_DEFAULT};

content/public/common/content_features.h

@@ -86,6 +86,7 @@ CONTENT_EXPORT extern const base::Feature kWebRtcHWVP8Encoding;
 CONTENT_EXPORT extern const base::Feature kWebRtcUseEchoCanceller3;
 CONTENT_EXPORT extern const base::Feature kWebRtcUseGpuMemoryBufferVideoFrames;
 CONTENT_EXPORT extern const base::Feature kWebUsb;
+CONTENT_EXPORT extern const base::Feature kImageCaptureAPI;
 CONTENT_EXPORT extern const base::Feature kWebVRExperimentalRendering;
 CONTENT_EXPORT
 extern const base::Feature kSendBeaconThrowForBlobWithNonSimpleType;

tools/metrics/histograms/enums.xml

@@ -22496,6 +22496,7 @@ from previous Chrome versions.
   <int value="-378180863" label="disable-panels"/>
   <int value="-378033324" label="disable-win32k-renderer-lockdown"/>
   <int value="-374657496" label="OmniboxEnableClipboardProvider:enabled"/>
+  <int value="-365920680" label="ImageCaptureAPI:disabled"/>
   <int value="-364325011" label="enable-files-quick-view"/>
   <int value="-364267715" label="disable-native-cups"/>
   <int value="-362022976" label="disable-quirks-client"/>
@@ -22861,6 +22862,7 @@ from previous Chrome versions.
   <int value="982032277" label="NTPOfflineBadge:disabled"/>
   <int value="982511393" label="NTPArticleSuggestions:disabled"/>
   <int value="983311394" label="tab-management-experiment-type"/>
+  <int value="988981463" label="ImageCaptureAPI:enabled"/>
   <int value="1000706989" label="AutomaticTabDiscarding:disabled"/>
   <int value="1002585107" label="emphasize-titles-in-omnibox-dropdown"/>
   <int value="1003002105" label="MaterialDesignBookmarks:disabled"/>