Revert of Enable HTMLMediaElement@autoplay on Android (https://codereview.chromium.org/447353002/)

Reason for revert:
I misunderstood the outcome of the discussion surrounding this topic. We need to keep this code in order to not break google.com while gathering data about this feature.

Original issue's description:
> Enable HTMLMediaElement@autoplay on Android
> 
> This CL sets user_gesture_required_for_media_playback to false in Chrome for
> Android. Previously, we removed this requirement as a special case for the
> Google Search Results page. Now that this setting matches Chrome's behavior on
> other platforms, we don't need the special case for google.com and can remove
> the entire VoiceSearchTabHelper.
> 
> This CL leaves the user_gesture_required_for_media_playback WebPreference
> because that's used by android_webview.
> 
> R=klobag@chromium.org, darin@chromium.org
> BUG=178297
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=288308

TBR=darin@chromium.org,klobag@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=178297

Review URL: https://codereview.chromium.org/453023002

Cr-Commit-Position: refs/heads/master@{#288389}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@288389 0039d316-1c4b-4281-b951-d872f2087c98

chrome/android/java/src/org/chromium/chrome/browser/Tab.java

@@ -121,6 +121,7 @@ public class Tab implements NavigationClient {
     // Content layer Observers and Delegates
     private ContentViewClient mContentViewClient;
     private WebContentsObserverAndroid mWebContentsObserver;
+    private VoiceSearchTabHelper mVoiceSearchTabHelper;
     private TabChromeWebContentsDelegateAndroid mWebContentsDelegate;
     private DomDistillerFeedbackReporter mDomDistillerFeedbackReporter;
 
@@ -794,6 +795,7 @@ public class Tab implements NavigationClient {
 
         mWebContentsDelegate = createWebContentsDelegate();
         mWebContentsObserver = new TabWebContentsObserverAndroid(mContentViewCore.getWebContents());
+        mVoiceSearchTabHelper = new VoiceSearchTabHelper(mContentViewCore.getWebContents());
 
         if (mContentViewClient != null) mContentViewCore.setContentViewClient(mContentViewClient);
 
@@ -960,6 +962,7 @@ public class Tab implements NavigationClient {
         mContentViewCore = null;
         mWebContentsDelegate = null;
         mWebContentsObserver = null;
+        mVoiceSearchTabHelper = null;
 
         assert mNativeTabAndroid != 0;
         nativeDestroyWebContents(mNativeTabAndroid, deleteNativeWebContents);

chrome/android/java/src/org/chromium/chrome/browser/VoiceSearchTabHelper.java

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser;
+
+import org.chromium.content.browser.WebContentsObserverAndroid;
+import org.chromium.content_public.browser.WebContents;
+
+/**
+ * Tab helper to toggle media autoplay for voice URL searches.
+ */
+public class VoiceSearchTabHelper extends WebContentsObserverAndroid {
+    private final WebContents mWebContents;
+
+    /**
+     * Create an instance of VoiceSearchTabHelper.
+     *
+     * @param webContents WebContents to update media autoplay status.
+     */
+    public VoiceSearchTabHelper(WebContents webContents) {
+        super(webContents);
+        mWebContents = webContents;
+    }
+
+    @Override
+    public void navigationEntryCommitted() {
+        nativeUpdateAutoplayStatus(mWebContents);
+    }
+
+    private native void nativeUpdateAutoplayStatus(WebContents webContents);
+}

chrome/browser/about_flags.cc

@@ -1295,6 +1295,15 @@ const Experiment kExperiments[] = {
     kOsAll,
     MULTI_VALUE_TYPE(kDefaultTileHeightChoices)
   },
+#if defined(OS_ANDROID)
+  {
+    "disable-gesture-requirement-for-media-playback",
+    IDS_FLAGS_DISABLE_GESTURE_REQUIREMENT_FOR_MEDIA_PLAYBACK_NAME,
+    IDS_FLAGS_DISABLE_GESTURE_REQUIREMENT_FOR_MEDIA_PLAYBACK_DESCRIPTION,
+    kOsAndroid,
+    SINGLE_VALUE_TYPE(switches::kDisableGestureRequirementForMediaPlayback)
+  },
+#endif
 #if defined(OS_CHROMEOS)
   {
     "enable-virtual-keyboard",

chrome/browser/android/chrome_jni_registrar.cc

@@ -36,6 +36,7 @@
 #include "chrome/browser/android/uma_bridge.h"
 #include "chrome/browser/android/uma_utils.h"
 #include "chrome/browser/android/url_utilities.h"
+#include "chrome/browser/android/voice_search_tab_helper.h"
 #include "chrome/browser/autofill/android/personal_data_manager_android.h"
 #include "chrome/browser/dom_distiller/dom_distiller_service_factory_android.h"
 #include "chrome/browser/dom_distiller/tab_utils_android.h"
@@ -177,6 +178,7 @@ static base::android::RegistrationMethod kChromeRegisteredMethods[] = {
   { "UmaBridge", RegisterUmaBridge },
   { "UrlUtilities", RegisterUrlUtilities },
   { "Variations", variations::android::RegisterVariations },
+  { "VoiceSearchTabHelper", RegisterVoiceSearchTabHelper },
   { "WebsiteSettingsPopupAndroid",
     WebsiteSettingsPopupAndroid::RegisterWebsiteSettingsPopupAndroid },
 #if defined(ENABLE_PRINTING) && !defined(ENABLE_FULL_PRINTING)

chrome/browser/android/voice_search_tab_helper.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/android/voice_search_tab_helper.h"
+
+#include "components/google/core/browser/google_util.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/web_contents.h"
+#include "content/public/common/web_preferences.h"
+#include "jni/VoiceSearchTabHelper_jni.h"
+
+using content::WebContents;
+
+// Register native methods
+bool RegisterVoiceSearchTabHelper(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+static void UpdateAutoplayStatus(JNIEnv* env,
+                                 jobject obj,
+                                 jobject j_web_contents) {
+  WebContents* web_contents = WebContents::FromJavaWebContents(j_web_contents);
+  content::RenderViewHost* host = web_contents->GetRenderViewHost();
+  content::WebPreferences prefs = host->GetWebkitPreferences();
+
+  // In the case where media autoplay has been enabled by default (e.g. in
+  // performance media tests) do not update it based on navigation changes.
+  //
+  // Note that GetWekitPreferences() is 'stateless'. It returns the default
+  // webkit preferences configuration from command line switches.
+  if (!prefs.user_gesture_required_for_media_playback)
+    return;
+
+  prefs.user_gesture_required_for_media_playback =
+      !google_util::IsGoogleSearchUrl(web_contents->GetLastCommittedURL());
+  host->UpdateWebkitPreferences(prefs);
+}

chrome/browser/android/voice_search_tab_helper.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_ANDROID_VOICE_SEARCH_TAB_HELPER_H_
+#define CHROME_BROWSER_ANDROID_VOICE_SEARCH_TAB_HELPER_H_
+
+#include "base/android/jni_android.h"
+
+bool RegisterVoiceSearchTabHelper(JNIEnv* env);
+
+#endif  // CHROME_BROWSER_ANDROID_VOICE_SEARCH_TAB_HELPER_H_

chrome/browser/media/encrypted_media_browsertest.cc

@@ -234,6 +234,13 @@ class EncryptedMediaTestBase : public MediaBrowserTest {
     title_watcher->AlsoWaitForTitle(base::ASCIIToUTF16(kEmeKeyError));
   }
 
+  virtual void SetUpCommandLine(CommandLine* command_line) OVERRIDE {
+#if defined(OS_ANDROID)
+    command_line->AppendSwitch(
+        switches::kDisableGestureRequirementForMediaPlayback);
+#endif  // defined(OS_ANDROID)
+  }
+
   void SetUpCommandLineForKeySystem(const std::string& key_system,
                                     CommandLine* command_line) {
     if (GetServerConfig(key_system))

chrome/chrome_browser.gypi

@@ -109,6 +109,8 @@
       'browser/android/uma_utils.h',
       'browser/android/url_utilities.cc',
       'browser/android/url_utilities.h',
+      'browser/android/voice_search_tab_helper.cc',
+      'browser/android/voice_search_tab_helper.h',
       'browser/android/webapps/single_tab_mode_tab_helper.cc',
       'browser/android/webapps/single_tab_mode_tab_helper.h',
       'browser/app_controller_mac.h',
@@ -2811,6 +2813,7 @@
       'android/java/src/org/chromium/chrome/browser/UmaBridge.java',
       'android/java/src/org/chromium/chrome/browser/UmaUtils.java',
       'android/java/src/org/chromium/chrome/browser/UrlUtilities.java',
+      'android/java/src/org/chromium/chrome/browser/VoiceSearchTabHelper.java',
       'android/java/src/org/chromium/chrome/browser/WebsiteSettingsPopup.java',
       'android/java/src/org/chromium/chrome/browser/infobar/AutoLoginDelegate.java',
       'android/java/src/org/chromium/chrome/browser/infobar/ConfirmInfoBarDelegate.java',

content/browser/media/encrypted_media_browsertest.cc

@@ -125,6 +125,13 @@ class EncryptedMediaTest : public content::MediaBrowserTest,
     title_watcher->AlsoWaitForTitle(base::ASCIIToUTF16(kEmeNotSupportedError));
     title_watcher->AlsoWaitForTitle(base::ASCIIToUTF16(kEmeKeyError));
   }
+
+#if defined(OS_ANDROID)
+  virtual void SetUpCommandLine(CommandLine* command_line) OVERRIDE {
+    command_line->AppendSwitch(
+        switches::kDisableGestureRequirementForMediaPlayback);
+  }
+#endif
 };
 
 using ::testing::Combine;

content/browser/media/media_source_browsertest.cc

@@ -46,6 +46,13 @@ class MediaSourceTest : public content::MediaBrowserTest {
     RunMediaTestPage("media_source_player.html", query_params, expectation,
                      true);
   }
+
+#if defined(OS_ANDROID)
+  virtual void SetUpCommandLine(CommandLine* command_line) OVERRIDE {
+    command_line->AppendSwitch(
+        switches::kDisableGestureRequirementForMediaPlayback);
+  }
+#endif
 };
 
 IN_PROC_BROWSER_TEST_F(MediaSourceTest, Playback_VideoAudio_WebM) {

content/browser/renderer_host/render_process_host_impl.cc

@@ -1238,6 +1238,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
 #endif
     switches::kLowEndDeviceMode,
 #if defined(OS_ANDROID)
+    switches::kDisableGestureRequirementForMediaPlayback,
     switches::kDisableWebRTC,
     switches::kEnableSpeechRecognition,
     switches::kMediaDrmEnableNonCompositing,

content/browser/renderer_host/render_view_host_impl.cc

@@ -416,6 +416,11 @@ WebPreferences RenderViewHostImpl::GetWebkitPrefs(const GURL& url) {
   }
   prefs.use_solid_color_scrollbars = ui::IsOverlayScrollbarEnabled();
 
+#if defined(OS_ANDROID)
+  prefs.user_gesture_required_for_media_playback = !command_line.HasSwitch(
+      switches::kDisableGestureRequirementForMediaPlayback);
+#endif
+
   prefs.touch_enabled = ui::AreTouchEventsEnabled();
   prefs.device_supports_touch = prefs.touch_enabled &&
       ui::IsTouchDevicePresent();

content/public/common/content_switches.cc

@@ -880,6 +880,10 @@ const char kEnableWebRtcHWVp8Encoding[]     = "enable-webrtc-hw-vp8-encoding";
 #endif
 
 #if defined(OS_ANDROID)
+// Disable user gesture requirement for media playback.
+const char kDisableGestureRequirementForMediaPlayback[] =
+    "disable-gesture-requirement-for-media-playback";
+
 // Disable the click delay by sending click events during double tap.
 const char kDisableClickDelay[]             = "disable-click-delay";
 

content/public/common/content_switches.h

@@ -248,6 +248,7 @@ CONTENT_EXPORT extern const char kEnableWebRtcHWVp8Encoding[];
 #endif
 
 #if defined(OS_ANDROID)
+CONTENT_EXPORT extern const char kDisableGestureRequirementForMediaPlayback[];
 CONTENT_EXPORT extern const char kDisableClickDelay[];
 CONTENT_EXPORT extern const char kDisableOverscrollEdgeEffect[];
 CONTENT_EXPORT extern const char kDisableWebRTC[];

content/public/common/web_preferences.cc

@@ -138,7 +138,7 @@ WebPreferences::WebPreferences()
       force_enable_zoom(false),
       disallow_fullscreen_for_non_media_elements(false),
       double_tap_to_zoom_enabled(true),
-      user_gesture_required_for_media_playback(false),
+      user_gesture_required_for_media_playback(true),
       support_deprecated_target_density_dpi(false),
       use_legacy_background_size_shorthand_behavior(false),
       wide_viewport_quirk(false),

content/shell/app/shell_main_delegate.cc

@@ -146,6 +146,10 @@ bool ShellMainDelegate::BasicStartupComplete(int* exit_code) {
     command_line.AppendSwitchASCII(switches::kTouchEvents,
                                    switches::kTouchEventsEnabled);
     command_line.AppendSwitchASCII(switches::kForceDeviceScaleFactor, "1.0");
+#if defined(OS_ANDROID)
+    command_line.AppendSwitch(
+        switches::kDisableGestureRequirementForMediaPlayback);
+#endif
 
     if (!command_line.HasSwitch(switches::kStableReleaseMode)) {
       command_line.AppendSwitch(